Many people get chickens, turn them loose to fend for themselves, and toss them a handfull of scratch every so often and expect to find eggs. Eggs require proper nutrition as well as a secure environment.
If their hens aren't receiving a daily ration of a well-balanced layer or flock raiser feed with oyster shell on the side to round off calcium needs, it's quite possible they are suffering from a mineral and vitamin deficiency, thus the tendency to pick feathers and have thin egg shells.
If their living quarters are infested with lice or mites or fleas, this will adversely affect their health, as well. Egg laying will also suffer.
If you want to help, take a flashlight and look around the coop after dark to see if you see any mites on the perches. Examine the birds, especially around the vent, for mites or lice. Suggest they give the coop a good cleaning and dust it liberally with Sevin.
If the chickens aren't being fed a proper diet, that's easily fixed by purchasing a sack of layer feed. People have had wonderful results by feeding fermented feed to improperly nourished chickens. To find out more about this type of feed, visit the fermented feed thread on the "feeding and watering" forum.
