Terminate her month to month tenancy NOW with the appropriate written notice (no cost to you except, perhaps, a postage stamp).3. 

with BORIC ACID, cut some 1 inch by 1 inch squares of light cardboard, like shirt cardboard and make a thin SANDWICH out of the paste.Put these around the kitchen and bath, inside of cabinets, very effective.BTW, the "mix some from another pile" thing with fire ants actually doesn't work.

The "out" for exclusive use is that if your Mom used that same piece of property too, it wasn't the lawyer's exclusive use and that should defeat a claim of adverse possession.Here's a good article: https://www.nolo.com/legal-enc...My first instinct would be to break the chain of continuous use by setting up a "no trespassing" sign and taking a date stamped photo. 

My businessman brother chided me a lot during the downturn about “losing my shirt” because property values dropped (they’re back stronger than ever today!).