Is it permissible to give the stepfather a share of the proceeds of usurious money, given that the husband is unemployed and the wife is responsible for supporting the family?

It is permissible to dispose of usurious interest by giving it to those in need, including your mother's husband if he is needy, because his maintenance is not obligatory upon the questioner. It should be noted that it is not permissible to engage in usurious transactions, and money should be saved in Islamic banks.