Is it permissible for children to ward off harm from their mother, who is being subjected to harassment and financial extortion by her brother and his wife's family, without her permission?

The intent behind "repelling harm from the mother without her permission" is unclear. If it means speaking with the maternal uncle and his wife to clarify that the mother is not obligated to provide the money they demand, then this is permissible as long as the mother is not harmed by this action. It is advisable to encourage the mother not to bear what she cannot tolerate and to apologize to her brother for what is not incumbent upon her. If she refuses and wishes to give her money to her brother and his children, there is no sin upon her, intending thereby the pleasure of Allah. It must be noted that the mother is not permitted to give the children's money to her brother or anyone else except with their permission.