And she even had purchased and installed new curtains for me.

If nothing else works consider changing the locks, installing a lockbox with a key and leave a note explaining they have to call you for access.

I've used Odor-Xit with some success after a deep clean, and sealing with BIN primer, but this was on the subfloor, which I then installed new flooring over. 

Installed new flooring and painted the entire house.

Most of which came from installing HVAC into both units.

When we rehabbed his studio the carpet install guys insisted we needed a hazmat cleanup team & literally walked off the job.We got the place & within 30 months (& after a LOT of work & some structural redesign) we got the property approved as a legal 6-plex & the rents are currently $4900/month.

Sure if they have renters insurance they should file a claim, and you can see if you get lucky and they cover the entire cost  also keep in mind that you’ll probably have mold, so that needs to be remidiated by bleach or something else before new boards are installed  Otherwise, since they are a decent tenant, I’d try to negotiate and work out a compromise with them.

Should you want pool, pump, well, solar panels covered there is a premium on top.

It also helped that we installed it in house.

I have tenants that are landscapers (total of about 10 of my tenants), handymen, truck drivers, tow truck driver, install flooring (2), etc.