Since your mother is already having issues about not understanding contracts

I would get a durable poa. Not just a plain one, but a durable one. This will protect both you and her. All creditors will accept it and talk to you then. You will need one for each parent. DO NOT ADD HER NAME to bills in just his name. Creditors will not be able to touch her for debts in his name only if domething hapoens to him.
A durable can only be changed by the individual if they are of sound mind, ir a court rules it dissolved. I won’t go into why this can be very important with my horror story. Just know it will protect all concerned.