I would use a professional grade ozone machine to remove any odors.

What if you smell a foul odor or smoking?

Check for strange odors either outside near the tank or inside the house.2. 

I am also concerned the extreme odor can seep into materials like the ceiling tiles, but would try the wall treatment first.

That would fall under "noxious odors".Paying her to relocate might be best and a signing that lease is terminated with the agreement and as soon as you have the keys when the relocation happens you change the locks for all entry doors immediately.

High levels, and low levels, of chlorine will both produce strong odors. 

You will see many people grumbling about inspections of one software or another.  

Only a few rooms have carpet which gives off a slight musky odor.

He detected a faint odor in the bathroom when he originally walked in.

He has been unable to unpack (for fear of infesting his belongings, probably too late), or even live in there because of the fumes/odor, and the fleas STILL REMAIN.