Hi
I really think it would be a good idea to try to speak to her even if you haven't in a long time. Parents can be very hard to talk to, and just someone showing that they care can mean the world.
There was a person next door to me once who guessed I wasn't feeling well so she gave me a ball and let me use their hoop in the backyard, she let me do her puzzles and walk the dog. Little things like that just made me feel that someone cared.
I don't know much about your niece or you, but maybe you could help her in similar ways.
I'll send her a prayer and hope she gets better.