I ended up using AXA. There were a few I had narrowed it down to but I needed to pick and I was running around in circles so I just bought it. Not the best way to do it lol but it should do what I need. I learned it takes a lot of research, you need to know your numbers of trip cost, and it's very personal to your exact trip. I added the cancel anytime feature as I don't want to lose it all just because I don't want to travel but the airline says it's safe. As a student your niece could very likely be in the "going unless the government says no" group so that feature may not be important to her, on the other hand if her school cancels her program but the airline doesn't cancel her flight are you covered? It just depends on her/your situation. And at the end of the day it might just be too expensive to be worth it. Personally I also liked the insurance covers expenses if I get stuck in a quarantine (something cc don't cover) but again since you're dealing with a study abroad thing she might already have that covered....
Since it's a study abroad program there might be specific insurance options the program recommends for students, I have vague memories of being required to buy some insurance thing when I went to China many moons ago.
Keep an eye on her program, a few US schools have closed their current study abroad programs in Florence and recalled students home, some are giving students the option to go home and some are proceeding as normal. NYU is closed through end of March a few others are closed indefinitely. ABC article on it
here.