What is the Sharīʿah's ruling on a mother's request not to marry a divorced woman who has a son, and what should the questioner do regarding her, and has the Sharīʿah obligated prioritizing marriage to a virgin over others?

Obeying parents is obligatory in matters that do not involve disobedience [to Allah], unless it causes harm to the child. If their disapproval of their son's marriage is not based on legitimate reasons, then he is not obliged to obey them. The choice of a wife is the son's right, and it is recommended to marry virgins unless there is a reason otherwise.