My mother is very stubborn. How do I get her to sign papers for me to handle her medical bills, food stamp account, many other papers?

I have the same problem. In addition to what you posted - I need copies of medical reports, names of doctors, to be added to her new doctor's list of people able to access and talk about her medical issues. I used to have these things then my mother started cancelling her all her follow-up medical appointments because she "feels too sick" or is "in too much pain" to go to the doctor (her reasons)! She doesn't want to ride in the car because it hurts her back, doesn't want to get out of bed or leave the house when she doesn't feel well - even for conditions that get to the point where most people would go to an emergency room. Then she switched doctors - away from the good doctor that wanted to get to the root of her health issues and to a doctor that is closer to her home and willing to refill her prescriptions without giving her care. I don't know what to do.