Any confrontation should be avoided as it will likely harm your case, not hers. 

We were left with two tenants (in the same unit) who did not go along with the ordinance whom we confronted and had a discussion about continuing to live in the building or moving on.

I dont understand how being agressive and confrontational at this point in the game will help you. 

I HOPE that she follows through on that, or I will be confronting her again when the next bill comes in.

HOWEVER, since anxiety is a legitimate medical condition with which a service dog can be required, many times, just the approach of the discussion prompts a panic attack since the questioner (in some cases) is less than cordial in their asking OR the service dog handler anticipates a confrontation that may never take place in the first place.  

You might also confront them about the person they moved in, but the easier issue to get them out on would be smoking.

It’s just not who I am, I’m really NON-Confrontational.

The only downside to this whole situation is now you have to send a different contractor to work on her unit to avoid a potential confrontation which sort of stinks considering you have a 15 year history with the contractor.

I tend to avoid confrontation anyway, but on the tenant's turf with threatening friends and no long-term track record with the tenant, I would have taken a more "oh, new locks?

I had a tenant I had to confront on this point and he did not realize I knew about a prior charge which was in the local police log until I mentioned it.