Family and Situation
Mrs. Wickham is the deceased wife of former Pemberley steward Mr. Wickham and mother of George Wickham. We never hear of her having any children besides George.
Character
Fitzwilliam Darcy implies that the reason her husband, Mr. Wickham, was unable to pay for his own son’s education was that he was “always poor from the extravagance of his wife.” Since the late Mr. Wickham is generally reputed to be a respectable man, it may well be that it was Mrs. Wickham who indulged her son George or even set an example for what he has become by the time the novel begins.