Nicotero also said that there were 3 graves, only one was empty, which was Lori's because there wasn't much left. He said that on the aftershow. Carol is gone. They buried her, which is why Darryl put the flower on her grave. He knows she is there. Unless I misheard, but I am pretty damn sure Greg said Lori's is the only grave that was empty. I still have it on DVR, I will rewatch.