Many breeders, myself included, feed a measured amount of pellets per rabbit per feeding. My rabbits run out of food all the time. They are always at their peak physical condition, excellent producers, and disease free. Free choice feeding of rabbits usually ends up with unhealthy, fat, illness prone, animals. Many overfed does have problems conceiving due to large fat deposits interfering with the reproductive organs. Free choice hay is not a problem, and actually beneficial.
As long as the rabbits are being fed daily, there is no concern, but as another poster previously mentioned, we don't know the specifics or history of the situation, and what the grandmother considers "not fed". In any event, one, or more parties involved needs to do some reading. Knowledge is power.