My mom, who lives in Pennsylvania, has dementia and won't seek medical care. Any advice?

I live with my mom who has dementia no power of attorney or a will. She will not take her medicine or see any doctors since the doctor told her she has dementia. We are concerned about my mother's well being, guardianship, power of attorney and a her having a will. My sister and I are worried about her well being and the above documents that should be in place for her to pay her home bills and medical bills if she were to have a terrible accident or get very ill that we would have to take over paying her bills and medical expenses. She does have the money to pay all her bills but doesn't have the important documents in place. She refuses to take her Alzheimer's medicine and see her medical doctors. How can we gain power of attorney guardianship and get a will in place? We all live in northeast Pennsylvania but I live with her so am main care giver.