Is it permissible for a wife to buy a house in her name with money sent by her husband to buy a house, without his knowledge or consent, and for her to refuse to return it to him?

If a husband sends money to his wife for her to purchase a house for him, and he does not gift her the money or the house, then the wife does not own the house, and it is not permissible for her to take it except with his permission. She must return it to him if he requests it, as her status is that of an agent who has no power to act beyond what the principal's permission entails.