@Bob B. I couldn't agree more. The owner is doing the tenant a favor by renting it to her for under market value. As an owner, I expect the same communication, respect and common courtesy from my tenants that I give to them. When that stops happening on their end, the relationship needs to change. It's not "aggressive" or "confrontational," it's being fair, but firm. You don't need to spend a lot of money getting a lawyer involved at this point, because there are steps you can take right now without needing one.
If you are concerned about your tenant's physical well-being, you can have the local sheriff do a wellness check. It's Florida (lots of elderly people here); they do it all the time.
Assuming she's fine, I'd send her the 15-day non-renewal. If she is not respecting you as the owner and communicating with you now, things are not going to get any better by sending her lease papers. This relationship seemed to have soured after closing and probably can't be salvaged. Send the notice by regular first class mail, certified mail and have someone local post it on the door in a conspicuous place (put it up with good heavy tape & protected from rain or covered with plastic) and take a picture of it for your records. (F.S. 83.56(4)
You can have your contractor go in for the mold remediation or any other maintenance you need to do for the "protection or preservation of the premises." Follow the guidelines in F.S. 83.53. If the tenant is not communicating with you, that falls under the "tenant unreasonably withholds consent" clause and you can post a notice on the door at least 12 hours in advance. Follow the same posting guidelines as stated in the previous paragraph. The contractor can then enter between 7:30am and 8pm to get done what they need to do.
After the 15 days are up and she's still not out, then you need an attorney to start the eviction process for holdover. If you go this route, you'll have to stop accepting rent payments too.
All of the Florida Statutes are online; I have them bookmarked and consult them as necessary. The ones that deal with residential tenancies are listed under Title VI, Chapter 83, Part II.
By the way, it is not in my nature to want to do any of the things I just listed in this post. I wish everyone would do what they're supposed to do, keep their word on agreements (verbal and written) and be good, fair and honest with each other. Unfortunately this is not how the world works, and over the last several years of being in this business I've learned the hard way. Yes, it's disappointing, but ultimately it's your investment and you are the one responsible for the property. Since being in Florida, I've noticed that a lot of people here (tenants/ friends/ neighbors) have lots of opinions & suggestions on what I should do with my properties but yet have zero invested in it themselves. Take the lead do what you need to do to manage your property the way you want to.