Is it permissible for a wife to give charity or lend from her money that her husband gives her as an allowance, without his knowledge, and what if those to whom she lends or gives charity are people her husband would not approve of?

If the money given to the wife is her obligatory maintenance, then she has the right to dispose of it as she wishes, whether through charity or lending, with or without her husband's knowledge, as long as she is not a spendthrift. However, if the money is given to her to spend on herself, her children, and her household, she is an agent, and she does not have the right to dispose of it through charity or lending except with her husband's permission and knowledge. If the money is a gift to her, then she has absolute right to dispose of it as long as she is not a spendthrift.