Sold my brother a car

Do I sold my brother my old car a month ago and he was locked up this past week. He ask my mom to put in her name until he was able to put in his. He asked that the car be parked until he gets home but my mom is insisting she and her boyfriend drive it. My brother asked multiple times if I can park the car in the driveway until he gets home because that’s all he has. He also has the key with him in jail. My moM took it on herself today and have someone come get the car to start without keys 🤦🏻‍♀️ and is refusing to allow my brother switch his car into someone else’s name. I told her she’s wrong for what she’s doing. Advice?