In the final twist of the movie, it is revealed that Talia is actually the one to have climbed out due to Bane helping her get up the hole.
However, Bane's pure motivation during the events of the movie lead the audience to believe that his only motive is a more physical and structured one of the Joker of taking over Gotham.
It is never lead on that Bane is sympathetic to anyone during the movie, so why would he protect a young Talia and endure a great injury, just to save her?