Is the money that the wife receives from the state as study assistance, based on her husband paying taxes, exclusively her right, and is it impermissible for the husband to share in it except with her consent?

As long as the state provides this assistance to the students themselves, it is their property. And whatever the wife receives in financial aid from the state, it is her property. The fact that she became entitled to this aid because she is the questioner's wife, and that the questioner pays taxes, does not grant him a right to this aid. However, he has the right to prevent his wife from going out to study, or he may permit her on condition that she gives him a portion of the aid she receives from the state.