okay, well, first of all, here is what I have learned from having hermies....

-DO NOT keep their habitat too humid!! Fungus will grow and kill them. In fact, I keep mine in an open glass tank. Mine survive for a long time, and All I need to do is stick them in a bowl of DECLORINATED water for about 2 minutes at a time, once a week.

- As I mentioned before, make sure the water they drink and bathe in is declorinated! That means no tap water. Bottled water is fine, and you can also buy declorinator at your local pet store. Chlorine is poisonous to the little guys!

- Are they getting sand in their shells? If so, this may cause them to come out of their shell and become a "nudie". If they are exposed too long, they will die. If this occurs, please tell her to first boil the new shell, (without the crab in it, of course!) then, place the crab in a small glass with the shell. if it doesn't go in by itself, gently rap it on the head and try to ease it back in. We saved one of our hermit crabs' lives with this procedure!

Hope this helped- feel free to ask if you have anymore questions!