The Super Sagas do not tell us the name of Doc's mother. All we know about her is that she died before the events in The Man of Bronze. Later raconteurs have proposed two different women for this role.
In his magisterial Doc Savage:His Apocalytic Life, Philip José Farmer proposed that Arronaxe Larsen - the granddaughter of Ned Land and daughter of Wolf Larsen - was Doc's mother. He makes this case in several other articles and books. His case seems water tight.
In the 2nd DC Comics Doc Savage series, issues #22 and #23 propose another woman, Brenna, as Doc's mother. She is a raven haired beauty with brown eyes. According to the story, her ex-husband Edgar Thayle recounted that on the night she gave birth to Clark Junior on the Schooner Orion, he attempted to kidnap the child because he thought that HE was his real father, not Clark Senior. A battle ensued and Brenna, her husband, and the baby escaped but Thayles was left for dead on the burning schooner. Supposedly seven years later he attempted to kidnap Clark Junior again in Siberia during the Tunguska expedition and he accidentally killed Brenna. An enraged Clark Senior then kills him. It is this savage act of vengence by his Father that starts young Clark thinking that there must be a better way to handle criminals than "an eye for an eye".
When I first read this alternative story of Doc's birth I was shocked. Farmer had made his case 20 years earlier for Arronaxe Larsen as Doc's mother and this new version clearly contradicted him. There was no way to harmonize both stories... or was there?
I consulted one of my my special sources and he told me the following story.
Brenna __________ had been the daughter of a wealthy stock magnate in New York. They were members of the Howard Foundation which since the late 19th century had been arranging marriages between people with family histories of longevity with the incentive of providing a financial endowments for each child they had. The Foundation was the brain child of millionaire philanthropist Ira Howard, who had died in 1873 of a rare form of progeria (premature aging) at age 48. He had begun arranging such marriages in 1860 after he had been diagnosed with his illness. His will established the Howard Foundation to carry on this work after his death. The usual standard was that each candidate had to have both sets of grandparents still alive and at least in their 70s. (This program has been described by Robert Heinlein in his stories about Lazarus Long.)
A young man named Edgar Thayles met this criteria, and he payed court to Brenna. The Howard Foundation doctors had certified him as healthy and fit for their program as they had done for Brenna. Edgar came from a poor background but he was ambitious and sought out a wealthy Howard Foundation subscriber in order to make his fortune. He thought that if he married such a woman, he would not only gain access to the Foundation's endowments but to her family's money as well. Edgar became obsessed with this idea and misrepresented himself to Brenna's family as a man of means. Brenna's parents were initially impressed but the truth eventually came out and they cooled towards him.
Brenna was a strong willed, independent 17 year old in 1900 and her parent's only living issue. Edgar was handsome, persuasive, and very charming. She eloped with him and they ran away together. Edgar intended to get Brenna pregnant as soon as possible reasoning that this would force her family to accept him as her husband. They had filed a falsified marriage license and Edgar knew that the marriage could be annulled on those grounds unless he made it socially impossible for that to happen. He acted purely out of selfish financial concerns though he continued to charm his lovely bride with his constant affection. He apparently had a sociopathic personality disorder with paranoid tendencies, delusions of grandeur, and manic-depressant mood swings.
Over several months he tried to impregnate her but it was to no avail. He started taking to drink. They were constantly on the move to avoid the private detectives that Brennas' parents had hired to find them and Thayles began participating in criminal activities and smuggling. The situation came to a denouement in Boston when Thayles announced to Brenna that to remain together, she needed to get pregnant by another man. She was horrified. Their relationship had started to deteriorate as Edgar drank more and this was a terrible blow. They had an argument and Edgar slapped her around and left their apartment to find her a "stud". Brenna left immediately and went to the home of her uncle who lived in Boston. He took her in and called her father. Brenna returned to her parents' home and they had the marriage annulled. Brenna grew up fast in those several months on the lam.
Thayles went to her home demanding that her parents give him back his wife. There was a violent scene and Thayles shot and wounded one of the _________'s servants. Her father filed criminals charges against Thayles, but Edgar disappeared and remained at large. Brenna went into seclusion after that for her own safety. She received several threatening letters from Edgar in the months that followed, but then that stopped and with time everyone forgot about him.
She met Clark Savage Senior in 1903 and there was immediate chemistry between them. Clark Senior always had a taste for strong-willed independent companions. With her checkered past, her parents had despaired that Brenna could ever find a proper husband. They took an immediate liking to Clark. He was an established financier in the city and known as the "son" of the author Richard Henry Savage by an earlier marriage. (This was a false identity that Clark had established a decade previously while he was studying at Harvard.) He had been recently widowed and had an infant son who needed a mother. After a whirlwind courtship, Brenna and Clark were married that year.
Thayles remained on the run and kept on drinking heavily. His mental state continued to deteriorate. He supported himself with criminal activities in the mid-west and New England. In a Gatsby-like maneuver, he hoped to win Brenna back with his new found -- but ill gotten -- wealth. But when he returned to New York, he discovered that she was already married and that she had a son that was just the right age to have been his!
At this point he became delusional. He was convinced that Clark Junior was actually his child and that Brenna had borne him in secret while she was in seclusion. He was convinced that this had all been withheld from him to deny him his rightful endowment from the Howard Foundation and his share in his wife's inheritance. Edgar could not accept that he was infertile and it drove him mad. (In all fairness, Edgar was likely not the one with the fertility problem. The Howard Foundation doctors had check sperm samples on him and found nothing wrong. In 1900, they had no good test for fertility in women and Brenna did not conceive in all the years of her marriage to Clark Savage Senior. The problem likely rested with her.)
Edgar hatched a plot. The Savages went on vacation in the Bahamas on their yacht, Orion II, and Edgar and some of his criminal cronies attacked the yacht with the intention of killing Clark and taking Brenna and the child. The attack occurred coincidentally near Andros Island where Clark Junior had been born.
During the voyage, Edgar hallucinated and imagined that Brenna was just giving birth to his child on that yacht and that he had to go and get them back NOW. He even became confused about what year it was. It was his delusion -- not the real history -- that he recounted in the Doc Savage DC Comic #22. The attack failed and the Savages escaped only to have to face Thayles again in 1909 with tragic results.
Brenna was the only mother that Clark Junior ever knew. While she was with him only a short time, she had a major impact on his life. She was always interceding with Clark Senior to go easier on his son and to give him a more normal childhood. She wanted him to play more and study less. She had come to love her stepson and was concerned for his welfare. The last time Clark Junior ever shed tears in sorrow was when she died. Whenever anyone would mention motherhood, it was her face he would see. After she was gone, Clark Senior intensified his son's training program and there was no one to oppose him. It was that intense training that made Doc into a virtual superman.
Edgar Thayles was a madman and he robbed Doc Savage of his mother. But it is possible that she would have sidetracked Doc's training and that he would not have become the hero we've come to know.