We see the girl with the glasses get shot. My interpretation of that scene is that she dies.
But then in the last scene when everyone standing outside the parliament take off their masks - there she is! The little girl with the glasses. Alive and well.
Why?
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I've said on another post that V is a metaphor for the individual, and that's what he was to those people who died, including Deitrich and the girl, and Evey's parents. The reason V has no real identity is so can represent everyone. Behind the mask, he could be anybody, and that's whats so important about him.
The characters appearing at the end were just another way of giving us that message, that, as Evey says, 'he was all of us'.