I worked with a wildlife rehab center for a few years and we would always get people brining in what they thought were abandoned bunnies and they almost always die from the stress in care. Unless you get them really young before eyes open they are old enough to know they should be afraid of you and the stress kills them. If they are really young with eyes still closed it is so much harder to feed them and they usually die from complications from that. I raised one that was brought in that was a few weeks old, he never stressed like the others did and fed really well but he could never be released due to a leg injury(the nest was run over by a lawnmower, killing all the other babies) so I ended up having to keep him. He died 2 years later suddenly for no reason, Just found him dead one day in his hutch!!
Just leave the bunnies alone, the mom is probably going back to feed them at 2 in the morning when no one is around!!