since i have power of attorney how can i get my 91 yr. old mother's name off a car loan for which she cosigned ?

My mother cosigned for a car loan over 5 years ago when she was in good health. The person she cosigned for is a poor pay and has had the car repossessed once, but managed to get the car back. The person is again in arrears and is at risk for another repossession. My mother is now 91 years old and suffers from pheumonia and dementia. She also requires 24 hour at home nursing care which has depleted most of her money. She cannot afford to pay for the car if it is repossessed again.