When I ran a property management company, tenants threatened us with lawsuits all the time without anything ever coming of it.  

She's now threatening to sue me for for not returning her deposit and for damage to furniture which she claims she incurred as a result of the squirrels and mice.  

In fact, here it is:https://www.dca.ca.gov/dca/publications/landlordbo...A book you should own is this one:http://www.nolo.com/products/the-california-landlo...It was my bible and I used their contracts, too, which are included.When tenants start threatening to sue or take legal action, it's best to remain calm and just say that if they choose to do that, that's fine, and you'll be happy to abide by the judge's decision if they decide to take the matter to court.  

At this point, you may still be able to give it try since  she may be literally threatening the deal. 

What you are trying to do is get the landlords to get a whiff of the potential for a lawsuit without actually threatening to sue.  

(This one is especially good for tenants who are hinting or threatening about taking you to court.)In fact, here's that website:http://www.dca.ca.gov/publications/landlordbook/pr...It's awfully nice of you to manage your Mom's property.  

If you feel like it threatens the tenant's safety and well-being then I'd foot the bill as the landlord and deal with the situation.

It's easy for these companies to send a threatening letter.

Wife threaten to sue me for "Elderly Abuse".   

Some tenants in the same income bracket will have a sob story and others will never ask for a favor.If this tenant has always come up with the rent, plus the late fees, every time you have threatened to evict - this is a budget priority problem.I heard it all as a manager.