Sorry, but although I was a bit vague where possible, most of this is a spoiler for the latter parts of the The Book of Eli. Please stop reading now if you've not already seen it. There are many surprises.
At the start of the movie The Book of Eli, the woman Solara seems a pretty average woman with lucky circumstances (the town was a dump & she was forced into prostitution, but she was a lot better off than most people in town and certainly better off than 'Trolley no-wheel lady'). Throughout the movie she goes through things which change her & make her realize just how horrid the 'outside town' world is, while also gaining strength & confidence.
She and Eli make it to the safe haven and he completes his mission to deliver to them 'the book'. In the closing moments, we see a discussion between her and the curator, where she mentions she is determined to go 'home'.
I thought that it was odd she'd want to leave, and expected to see her toting a big hulking copy of 'the book', now with her own mission, but there is no book in evidence. In fact, after she leaves the gates of the sanctuary (replete with Eli's weapons and possessions) we see the curator lovingly placing (what seems to be) the first copy of the first edition into its place in the bookshelf.
So.. where is 'home'?
One might think she means back to the town she came from. She had no way of knowing it might be worse for wear, but you'd think she would be determined to take a copy of the book whose words so moved her when she heard them (after learning how to read, obviously).
On the other hand, as Solara is traveling up the road away from the sanctuary, she disappears in a 'shimmer of heat wave'. She just vanishes. Was Solara actually some sort of 'guiding spirit' for what would be a difficult part of Eli's journey? Was 'home' actually heaven?
Note that her actions along the way did soften the stance of Eli, and at one point he even risked all so that she might be spared harm. It could almost be said that her presence helped bring him to the realization that he need not be so tied to a physical object. 'Mind the words, not the book'.