Is it permissible for the wife to keep her brother's money, which she obtained from a land exchange, in a bank account under her mother's name without his knowledge, under the pretext of securing his future and protecting him from bankruptcy due to his spending on unlawful things, knowing that the husband bears all household expenses and she is committed to her religious duties?

Your father-in-law should have been fair among his children. After his death, may he be prayed for mercy and forgiveness. We advise the wife to withdraw her money from the usurious bank. It is not permissible for her to take the usurious interest; rather, she should give it as charity to the poor and needy. The wife has the right to dispose of her money as a mature adult, as long as it is permissible, and it is recommended that she spend from it on maintaining kinship ties and charity. She may also advise her brother to fear Allah. The Sharia (definition) does not obligate the wife to spend, but her helping her husband is a good deed for which she is thanked.