Is a POA responsible for the persons debt after they have ped?

I was my grandmother's POA until she ped away in Jan 2009. The nursing home that she was at insist that I'm still her POA and responsible for a $2,000 bill. They have threaten to turn me into collections and everything. I have contacted my grandmother's lawyer and was told that I'm not responsible for the bill, they continue to send me a statement every month. My grandmother had no estate she had nothing when she ped thanks to her sister and two niece's. Her will was not taken through the courts due to the fact that she had nothing. I have received other medical bills for her and it was simply taken care of by sending a copy of her death certificate. I have sent them a letter advising them any further contact needs to done to my grandmother's lawyer. What else should I do?????