Is money saved from a wasteful father, and spent on a needy mother and charities, considered unlawful money? And what should be done with it if it is?

It is not permissible for children to take from their father's money without his permission and consent, unless the father is stingy and does not spend on those whose maintenance is obligatory upon him. In that case, they are permitted to take according to their needs in a reasonable manner without excess. It is not permissible to lie to the father to take additional money, though dissimulation (tawriya) may be used. Likewise, it is not permissible to give in charity money that exceeds their needs.