This is a bit of a unique situation but what you are describing is a constructive eviction, and will be trouble for you in court $$$.
As a landlord of 35 years, the best solution is "Here is a $1000 cash. I will give it to you when you pack up all your belongings and are sitting in the back of a taxi on your way to somewhere else. Otherwise I WILL evict you and you will have nothing."
It works.
So I guess, I can quit collecting snakes?
I always used the deposit for that approach.
Interesting proposition, and they could possibly get her to leave for less, then CHANGE THE LOCKS. Have her sign something to show that she acknowledges their prior agreement for her to work for them has been terminated at the mutual concession of both parties.
And if you slip the driver $100, you can keep the other $900