Plumbing is something to check out, most MF properties that old are going to have some backups in the sewer lines that will need remedying or replacement, so get some quotes and consider budgeting for that.

Then, you'll take the scope of work to a remediation company who will do the actual work (tearing out the mold contaminated materials).  

What (if anything) is pragmatic to say to her to remedy, prevent worsening, considering the weak pet addendum in her lease and my plan not to offer renewal?

I was talking to title companies about things that showed up on a title report and how we could remedy those.

Lender need not exhaust any remedies against Principle (Borrower) before seeking recovery from the Guarantor."

"Reality TV" is not reality in most casesHost:  "Your pipes are shot and leaking and there is mold everywhere in the walls this is TOTALLY going to blow your budget"<comes out of commercial>Owner: "Well after the $125 to re-do the pipes for our entire home and $25 for whole home mold remediation our budget was stretched really tight but I think we can sacrifice the vase in the guest room and still make it"

As a landlord, the immediate deal-breaker for me has always been the laundry-list of rules and regulations I'm required to abide by if I participate in the program; however, the agency is under absolutely no obligation to remedy debt or damage created by their voucher-holders.

Then we took things that were unnecessary out, fixed windows, ventilated basement with vents and fans(got rid of bugs), and did what I like to call brewed a batch of bootch, you can PM me for details (Chinese remedy for bugs).

You can explain the issue with the title company and listing agent and most of the time that will remedy any confusion the seller might have.

I won’t get deep into it; I’ll just give a remedy to the heated discussion which will solve the problem legally.