There is a theory that the boy is not really his son but a 'replacement' for the son the mother either lost or never had. This may also be why Eli mentioned that the boy looked nothing like him and it made him very upset. Who knows, maybe the boy actually found his real family in the end, but there are so many questions. See the start of this Thread.
No one has a name in "The Road", look at the cast and their movie role names:
Viggo Mortensen ... Man
Kodi Smit-McPhee ... Boy
Robert Duvall ... Old Man
Guy Pearce ... Veteran
Molly Parker ... Motherly Woman
Now there is a take that when the boy met the family in the end he was actually meeting his death. The children looked like they were not happy at all, the woman was all bubbly and the veteran was with no face of care, maybe just another meal? The deduction comes from the fact that we are shown that no one cares about no one in this film. Even the father who thought the boy he was the example of the "good" and carrying "the light" yet he ended up turning totally uncaring of others by the end of the film.
I think that's a bit of a stretch. It is obvious that under such circumstances, the kids could not possible look happy. I think we saw that side of the woman because she was just that...a woman who as a mother herself felt great sorry for the boy. I do not think they were cannibals, if they were the dog wouldn't be alive.
I did think about the dog, it makes you wonder where they are getting all that food from to be able to feed a dog, and two kids since they can hardly feed themselves as grown adults. From what I read the novel gives a positive ending but the movie ends in such a way to keep you guessing about what eventually happens with the boy. The original author of the novel: Cormac McCarthy gave the movie his blessing so I guess he felt it depicted it the way he saw it.
You guys are coming up with some interesting possibilities. There was an earlier comment about the thumbs missing. Seems from what I've read elsewhere is that when the civilized world came to an end people began coming together and enforcing their own laws and if you didn't obey your thumb was cut off. Now you have to think back about who in the movie had their thumb cut off.
Well that explains it but did you get that from someone who read the novel because it is not revealed in the movie. In fact The Road harly gives you any information like how the world ended up the way it did, the names of the characters, etc. I guess the whole idea is that in such a situation who cares because they are only thinking about where their next meal is coming from.
The Road (Hover)
Well they said they got that from the novel but I haven't read it so don't take my word for it.
There is also some possible reasons for the earth ending up that way: global warming, nuclear war, major earth quakes everywhere, meteor hits the earth but whatever it is the main thing it does is darkens the sky so no sunlight can come through to make things grow.