How will I transfer property when person is deceased?

My husband and I have entered into agreement with his sister who is power of attorney for her mother in law. Her mother in law owns house. I drew up agreements best I could. 1. Agreement for deed 2. Lease to purchase agreement 3. Lease. They were all filed at county courthouse. Along with the power of attorney. Agreement is for $50,000. no $ down, just $400. a month and I pay all taxes as of agreement. Agreement is for 10 years, no interest. She pays for all back taxes with lease to purchase payments. How will we transfer ownership/File Deed when her Mother in law has ped away? Thanks for any help.