It's difficult enough having fibro but being by yourself and also fragile makes it even more difficult. I'm so sorry she is going through this.
The physical therapy could very well strengthen her and they would give her tips on how to get around. My mother had a stroke and had to learn how to walk and dress and eat again and physical therapy was an absolute miracle for her.
As far as her dizziness is concerned, did this start after she started medication? Perhaps she needs a lower dose to help ease that. Some people just don't need much medication to get good results...and I'm one of them.
It's important that she take her medications properly. Get some pill boxes and fill them appropriately and that should help. I have four pill boxes that I fill once a month. That way I don't have to open containers all of the time and I can see if I've taken my medications, too. It's easy to forget if you've taken your meds or not...especially at her age...and you don't want her taking too much either. Of course, if she is incapable of doing this, she shouldn't be living alone in the first place and moving in with a relative or assisted living should be considered.
They might consider getting her a walker. Some have hand brakes and seats attached but it depends on her strength and balance as to what walker would be best.
They might want to get Meals on Wheels. These people usually stop in a visit for a few minutes when delivering the food. They could ask about that. On television I see ads for something called Visiting Angels...I think that's the name. These people come over, visit with the elderly, play cards with them, etc. This helps keep them more alert and I'm sure she would love the company.
Most communities have senior organizations that could probably offer more ideas. We have special busses in our community that picks up seniors and takes them wherever they need to go. There are also senior centers where she could go to play cards and visit with others her age. She would most likely need a ride unless they pick people up.
So, if her family will take the time to check these things out, these could help her. Depression is common with fibro and being alone could make her more depressed which would lead to more pain. But, if she has some things to look forward to, she might do far better. Plus, it could give her some life back. She wouldn't be sitting home thinking about how she is feeling. That's not good at all. If she has something to plan and look forward to, she would be happier. But, I personally think her first step should be physical therapy to get her strong and back on her feet.
I hope this helps you some. It's wonderful that you care enough to come here and ask for suggestions! You are a special person.
Sherrine