Stress can cause hair loss and this includes eyelashes. Thinning eyelashes could be the sign of a hidden medical condition, it might be a good idea to run it by her doctor. This is just my opinion, not medical advice.
Vitamins are beneficial to hair growth. There are several serums out there that are non prescription. Here are a few ideas: http://www.livestrong.com/article/17...-my-eyelashes/
The prescription is expensive, one bottle lasts about two months and I have yet to see an insurance company pay for it. Latisse is the name of the drug.
Some more info on the drug and prices: http://www.realself.com/question/how...s-latisse-cost