a couple of box fans + 20x20 filters.... run continuously 1-2 days. dump the filters directly into a trash bag. replace and re-run.have the ac/heat ducts (if any) professionally cleaned... you don't want to breath the nasties again....also i would check for cold/humid sections of walls. also crumbly (drywall/plaster) around baseboards. if you have those, (respectfully sorry) you are in for a surprise if you open the walls.....now, what is the source of humidity?

After permits ,elect,heating, costs and labor was appx 25k.

Usually:roof/foundationdoors windows trimTileplumbing/heating/elec/fans/vents while everything is exposed.hang and finish sheet rockVanity/sinksToilet/tubPaint ceilings and walls.Then light fixtures/cabinets/flooring/appliancesFinishing touches.

You have to control all elements at all times which admittedly can be difficult at times.Nothing I say should be substituted for legal advice from your attorney. 

It's a grueling process, giving tenant deadlines for each step, and give notice accordingly if she misses (making appointment, buying mattress covers and mattresses, heat treatment of all clothes and furniture).

How long did they look into each element of the project for a more exact time, price and evaluation of the task at hand?

We are looking for a certified gas technician who can remove an old gas stove for heating and install a brand new one in our rental.

Heating is also another factor.

Two months vs three months ...Maybe you let the one guy stay those two months if he is paying the utilities and agrees to continue to do so; you have the place getting the heat paid in winter that way, and that will save you some expense.No matter when they both move out, that would be when you gain possession back and at that time you account for damages to be paid from the security deposit.

I haven't checked the PA one but there's probably something similar.5-12-040 Tenant Responsibilities(c) Dispose of all ashes, rubbish, garbage and other waste from his dwelling unit in a clean and safe manner; (d) Keep all plumbing fixtures in the dwelling unit or used by the tenant as clean as their condition permits; (e) Use in a reasonable manner all electrical, plumbing, sanitary, heating, ventilating, air conditioning and other facilities and appliances, including elevators, in the premises;