We rescued the Peeper egg and he's hatched and killed the other chickens. I've talked to him and he's now follow us. I went back and tried talking to the ghost of big Marge but her only dialogue is to ask where peepers is. I can't progress the quest.
I have same problem, however quest can be progressed by finding rooster, but with only one option to leave Peeper alive which ends in quite annoying fight with respawning chickens. But in this case no reward