Am I responsible for my mothers back taxes and real estate property taxes

I am executor of my mothers estate. My father died and left her with 400,000 in 401k and life ins. She bought a small house and was living well on this money until she met a man(he had just gotten out of prison) that talked her into selling her house and buying some land and horses. He never got a job. They live off of my fathers soc sec which does not even pay the mortgage on property. They also have trail rides with horses, which I know is just change. I don't know if she files tax returns or pays property taxes. I know that she is close to forclosure. She has borrowed money from me several times to pay bills and mortgage payment, but I refuse to give her any more. I know that she is going to eventually lose this place, if she lives long enough. She is constantly begging for money from people and I love her and feel sorry for her, but she knows that from the beginning, I have not approved of this man who is a con artist, or their relationship. What I want to know is if she were to die, would I be responsible for any tax returns and property taxes that have not been filed and paid. I know her finances are in a mess and they don't pay their bills.