I think that being able to select evidence from the last two sections of the work and tie it into a theme is going to be contingent on what the reader sees as dominant themes in this section.  The theme of utter hopelessness is something that can be picked up on in these sections.  These are the sections when Eliezer feels that his father is a burden and the only hope he experiences is the "freedom" that when his father dies he is now able to think of his own survival.  Another theme that would be evident in these sections is that of death, in that the reality of death is the only constant (along with hunger) that accompanies Eliezer.  There is nothing else except death for him.  Another theme that can be seen in these closing portions of the narrative would be the dehumanization that became such a brutal part of the Holocaust.  At this point in the narrative, consciousness is only defined as a struggle to survive.  Eliezer thinks of nothing but food, bonds of solidarity and loyalty have been supplanted by the animalistic need to survive, and there is little to differentiate Eliezer's life from any other animal.  This might be a part of what he is unable to recognize when he sees his reflection in the mirror at the end of the narrative.