-If I do decide to wholesale it, do I need to take care of the flea infestation or the actual buyer?

I would think this falls under regular duties of the occupant unless there is evidence of a significant infestation.  

After calling the local franchise which had done a tenting about continuing infestation and repair, within 1 yr, they refused claiming it was old damage. 

Infested with mice and roaches.

They try to find less expensive but non crime infested neighborhoods, purchase old brownstone or greystone homes with solid bases, and totally gut + rehab them.

New tenant has complained about large infestation of fleas... she is mentioning wanting her money back... what should I do to mitigate the issue?

My biggest concern is that we have a great tenant who lives above him with no animals and I do not want her house to get infested with fleas.

Plus you don't want a full-fledged infestation so it's in your best interest to have it treated if a problem really exists.  

Since, at the time, I was into saving lives, I bought this house at full market value, paid all closing costs (remember, he and all of humanity was at deaths door), and purchased a mold infested one bedroom one bath in a shady neighborhood.

P.s...i dont know anybody that can see baltimore from california.....Pss baltimore is a profitable place, but run by and infested with morons.