The book’s last chapter opens up with this intriguing statement:
Time can play all sorts of tricks on you. (2.12.1)
And indeed, the end of the book does play around with time.
First, we see it skip forward six months to when Hugo is living with Georges Méliès and his family… And then in the last chapter, we realize that it’s skipped forward even more and that the narrator is Hugo telling his story in retrospect… It becomes even more interesting when it's revealed that the entire book has been written by an automaton, which is adult Hugo’s great invention.
How trippy (or rather, tricky) is that?
The ending reveals that Hugo, like his father and like Georges Méliès, has continued to create great things, and that this book is one of them. And as for the final sequence of drawings (I2.12.1-6), the fading moon seems to suggest that this story has indeed drawn to a close—and it’s a nice little nod to A Trip to the Moon, too.
What's key here is that Hugo's childhood story has come to a close, but it's very clear that it's only the beginning of a rich life, filled with inventions and adventures. Of course these inventions and adventures are only possible because in the end, Hugo has found what he's been searching for—a family.