What is the ruling on a husband preventing his children and wife from visiting her non-Muslim, morally corrupt family, knowing that the mother practices sorcery? Would the wife be considered as severing ties of kinship, and would the husband be sinful for preventing his children from visiting the wife's family?

It is not permissible for a husband to prevent his wife and her children from visiting her parents, as this constitutes cutting off ties of kinship. This applies even if the parents are disbelievers, based on the Almighty's saying: "And accompany them in the world with kindness" and the hadith of Asma bint Abi Bakr. However, if the husband fears harm to his wife and children from this visit, then he may prevent them.