Is it permissible for the wife to feed the poor from her husband's money without his knowledge if he broke an oath and refused to expiate for it?

It is not permissible to pay the expiation on behalf of another unless with their permission, because expiation is an act of worship for which intention is a condition for its validity. Therefore, the wife should convince her husband to pay the expiation, or that he permit her to pay it from his money or her own money.