What is the ruling on a sister preventing her brother from visiting their mother?

Allah has commanded righteousness towards parents and benevolence towards them, and this is among the best of deeds, while their disobedience is one of the gravest major sins. The Prophet, peace and blessings be upon him, specifically honored the mother with greater righteousness, for Paradise lies beneath her feet. Therefore, you must treat your mother kindly, and it is not permissible for you to obey your sister in not visiting her. Rather, you must advise your siblings and warn them against severing ties with their mother. You must also maintain kinship ties even if they treat you badly, and you are not obligated to divorce your wife to please anyone.