Aunt Clara appears and shames him because he hadn't waited for George....... she speaks in Lennie's voice, so I believe she represents his own sense of right and wrong, and the fact that he wanted to do what was right, but it didn't always end up that way,
The second vision is the giant rabbit (who also speaks in his own voice) and tells him that George will probably abandon him.... just leave him there
I'm not sure what the rabbit represents, except that maybe it's the end of the dream of the farm.
