Is it permissible for a wife to take money from her husband without his knowledge, to give in charity to the needy and the sick (including her poor siblings), out of a desire to help and to attain well-being, and is she considered sinful for rejoicing in her husband's loss of some of his money because he withholds it from her?

The wife's maintenance, including food, drink, clothing, and housing, is an obligation upon the husband according to what is customary and commensurate with his means. He is not required to pay a monthly allowance if he provides the aforementioned. It is not permissible for the wife to take her husband's money without his permission, nor to take wages for her work in the home. Rejoicing at the husband's loss is forbidden gloating (shamata), so the wife must repel such feelings and try to remedy them with wisdom.