Steve [Tompkins]once mentioned to me that it is worth considering why there is an almost complete lack of Mother-figures in Howard’s work. Is that big black hole where the hero’s mother should be indicative of some parental neurosis? Perhaps…but examples of stories lacking any mention of the hero’s mother are legion, and — thinking specifically of the pulp jungle — the last thing readers wanted was some old lady taking screen time away from the hero and damsel in distress. Those Brundage covers would start getting pretty scary.
–Leo Grin, In Defense of Hester Jane Ervin Howard

There is one mother figure that does stand out, as if to be the exception that proves the rule.  And that is the old witch Zelata, from The Hour of the Dragon.
True, her “children” are a wolf and an eagle, but her reception of the fugitive king, offering food and shelter (and death to his enemies) is quite motherly. She also shows him visions of things that have happened, and offers sound advice.  She is described as straight and tall, with clear-cut and aquiline features, not those of a common peasant woman. Howard clearly wanted this character to be impressive, and succeeded at making her so. In a fictional world full of sirens and sex toys, voluptuous babes and evil vixens, Zelata definitely stands out.