Your prior lease should have a clause in it that states it will continue month to month after it expires.   Since Landlord B purchased the property he/she also purchased your lease with Landlord A.   So you would be required to pay Landlord B rent.   Don't be a disrespectful person in life.  Don't look for stupid excuses to not pay rent.   If you do....  You lose your man card in life as a worthless person.