Should I ask them to leave and just look to fill both units fresh?  

If you list a brand-new home on the same street as a home which has been vacant 100+ days, there is a good chance fresh home will rent first, and the vacant unit will remain vacant.

Of course property inspection shouldn't reveal any major issues.

Now I have a new problem.After title search, it is revealed that in addition to the known back taxes, the seller also has mowing liens.

If not, let him leave, evict the druggie and start fresh with a tenant you can trust. 

Hello Amanda Gus  on Zillow its States 168000k and I checked the areas around  that house all the houses go between from 220,000k-260,000k and plus I checked on my fresh comps also  so my fresh comps that I signed up for Zillow and plus the comps that she has sent me in my area they not that far off as far as how much the house will be worth after I repair it but the 78k has threw me in for the loop which that's why I haven't put in an offer ask to see the inside of the house yet

More will be revealed as this process unfolds I'm sure.

My preference is to renew as per contract or that they would reveal the minimum commitment they are able to make, and we’ll write up a short term lease at a higher price - flexibility and stressing out the landlord should come at a cost.

Rented for 750, up to 775 now.2016 Rental #4 - Found thru Zillow 3bed/1bath 21,200- hired out the floor to be refinished, wow freshly refinished floors look amazing, proceed to do that to rental number1 after a major trashing(one of the few I've had).

Thanks @Jack D. love old Say Brook, Fresh Salt restaurant is amazing!