What should I do about my friend who steals to give to the needy, even though I have advised her that her action is unlawful?

Stealing money is a major sin, and the one who commits it will not be rewarded for it, because it is illicit gain, and Allah accepts only what is good. She must repent and return the money to its owners or seek their forgiveness. Her love for charity, even without money, will cause Allah to record for her the reward of her intention.