Medicaid lein on my house

This past July, my mother died. She was never in a nursing home, only the hospital. She only lived off partial social security and was eligible for medicaid. In her will, she stated that I was executor and all property was to go to me. I paid off the house and am in the process of having the deed switched to my name. Today, i get a letter stating medicaid wants to put a lein on her estate. I had lived in the house my whole life and my father died 7 years ago. I have paid all taxes. Can they force me to sell my home?