Is the husband obligated to help his disobedient brother who does not pray, deals in usury, unlawfully consumes people's wealth, and visits sorcerers, especially after he has repeated his previous actions and accumulated usurious debts again, and would the husband be sinful if he refused to help him?

The husband is not obligated to help his brother, nor is he required to obey his mother in this matter due to the presence of harm. He is not considered disobedient for not providing assistance. It is better to advise the brother to abandon sinful acts and to fear Allah. If he repents, then it is preferable to help him. However, if he persists in his ways, he should not be helped, as that would be aiding him in aggression. One should be gentle with the mother and apologize to her.