“his family / care takers could have prevented this.”
How? How do you prevent a legal adult from driving? Driving privileges are issued by the state, not the family.
I ask in all seriousness, because it is a valid question. They could talk to his doctor, or they could talk to the state, but only the state can revoke the privilege.
Taking away his keys or car is theft, and a felony.
It’s really quite simple - you talk to his doctor and he reports to the state and they pull the license!