Some families use a Discretionary Trust as a way for owning and managing of the home if they buy it for their relative.
The situation on paying rent is complicated but it may also be possible to claim Housing Benefit to help pay for the rent. Trustees will need to make arrangements, and pay, for repairs and maintenance.
Some families decide to buy a property and hold it in a trust because it gives their relative somewhere to live.
Mencap have information on setting up Trusts when buying a house: