Can you sell a home that is under a contract loan?

My Grandmother is in a Rent to Own Agreement.The Landlord stated that he purchased the property but after some research she has learned that a man that also happens to work for a bank (mortgage) is listed as the owner. Whn my mother approached the banker he stated that he gave the Landlord a contract loan on the home and that he (the banker) no longer owns the property. My grandmother says that under a contract loan you cannot sell property and she is ready to by the home. Is her Contract void?? Is this a possible scam??