Handling a tenant issue

[William SaintAmour]

Let me set the stage:

I have a 4 plex in Michigan.  The neighbor in the bottom unit smokes.  The neighbor above smelled it and brought it to my attention (we are a non-smoking building, it's in the lease).  I provided notice to the lower neighbor, and they stopped smoking in the apartment (at least for the moment).  The neighbor above says it has permeated to her apartment, and she cannot stay there.  Her lease is up in August 2021.

BUT about a month before all of this she let me know that she plans to move out to a SFR as soon as she can, and would like me to find a new tenant so she can break her lease. Between the holidays and COVID, there hasn't exactly been a line of qualified people wanting to move at the moment.

I'm sympathetic to the smoke complaint, and I have documented my action based on it.  I plan to visit her apartment personally and do an ozone treatment, and document that.  I'm happy to boot the downstairs tenant if they smoke again, and actually plan to boot them in the spring to clean their place up and get it to market rent levels (they were inherited).  I am not inclined to break the lease for the apartment above because of the smoke smell if it is not noticeable when I go in or after ozone treatment.  Am I taking the best path?  I don't want to keep a tenant if they want to move; however, I'm also not inclined to eat rent and utilities in the winter until I can fill the vacancy.

What am I missing? Better options?