Although Victoria had spent enough time with humans to return back to humanity, Lily was gone for good. She considered Mama as her mother, and her happiness laid more with Mama than anyone else.
Mama jumps off the cliff with just Lilly, and upon hitting the branch, Mama and Lilly turn into a shower of butterflies. The movie ends with Victoria realizing that one of the butterflies watching over her is in fact Lilly, perhaps referencing a ghostly regret of Victoria not going with her.
