There might be some remediation but I'd go and fix what's is still fixable. 1.

She did however have to deal with bat issues, and the fact that she had to remediate guano from the attic which can harbor dangerous fungi spores ect.In a home built between say '50s and '70s then asbestos may be a huge item to look for.

., I'm coming up with most possible worst case scenarios and pricing it out so it's repaired or remedied within a week. 

Put your offer to let her out of the lease and repay her past electric bills in writing along with your decision that the alternative remedy is for her to continuing the lease with her paying for the electric as it is, deliver your offer/decision in person and by certified mail return receipt requested.   

While I’m not looking at doing so, I absolutely don’t want them stuck without heat, so I’ve purchased them 4 good space heaters which should sufficiently warm the home until my HVAC guy can get the install done.My tenants are wanting the problem remedied as soon as possible, but the replacement may not be done for a week and a half or two weeks.

That is a lot of YOU even though you have an LLCwe have lead paint rules.... we have to mitigate lead paint before we rehab old houses and the other one is asbesto's I got tagged for a 35k fine and remediation on that one  LOL.. so I get lead paint inspection and asbestos before we start.I did see that American greed show were the land lord did nothing about lead paint and the child ate the chips and died.. and I believe he got PERSONALLY criminally indicted I don't think any asset protection was going to save him there.. 

Failing to properly remediate after an ongoing water leak can come back to bite you later when mold develops, so be sure you have people that are properly licensed and insured to deal with all of the repairs.In reality there is no way to know exactly what the source of the leak is, until the ceiling is opened.

Are there any remedies or proactive measures the homeowner should take to safeguard his interest?

These are Philadelphia row-homes.According to my neighbor, effort has been made since 2016 to have this issue dealt with by the property owner, even going so far as to involve L&I as well - to no avail.I decided to reach out to a real-estate lawyer I dealt with some months ago for an unrelated matter, who recommended I reach out to an arborist as well as a foundation repair specialist to estimate costs for remediation. 

Loan Info:$74500 Purchase Price (Down Payment $18,093) Loan Amount: 59,600Interest rate: 4.375% (Redfin estimate listed as $121k/Appraisal listed as $74,600)Repairs Required:- Roof certification confirming remaining economic life of no less than 2 years or proof of roof repair/replacement by a licensed roofing contractor- Plumbing inspection and certification from a licensed professional; repairs as indicated- Electrical inspection and certification from a licensed professional; repairs as indicated- Structural Report to be completed by a licensed engineer; remediation/repairs as indicated- Chimney must be inspected by a licensed professional and repairs completed.