S.B.
Well, at least in California, if NOTHING is signed after the original lease runs up and you still occupy the house, it automatically reverts to a month-to-month situation. You are only required to give a 60 day notice and the landlord is only required to do the same if they want you to vacate (although I've seen many landlords accept or impose a 30 day notice).
If there is no lease, no contract, either protecting you or binding you through a certain date, it's month to month.
....At least in California.
Best wishes.