Your Niece is running the main period of Saturn and sub period of Rahu. Saturn is posited in the 8th house and has aspect of Rahu. Her Moon is also very weak as it is debilitated in her natal chart. You should make her do two remedies.
1. Make her weak Chandi ka kara.
2. Every Saturday take some Sarson ka tel and ask her to see herself in the tel and later you can donate it.
3. Use Haldi over the area which is getting affected and as Haldi has lot of natural properties surely it can help.
These days the medical science is very advance so give her the best treatment. I was just reading on the Internet that is it a curable disease. I’m sure the Almighty God will bless her always.