Complex sentence: When Annabel offers Mama the remains of her child, Mama transforms to the beautiful woman she was before she died and is about to die peacefully, finally reunited with her child, but Lilly calls out for her.
Split into simpler sentences: When Annabel offers Mama the remains of her child, Mama transforms into the beautiful woman she was before she died. Before she is to die peacefully, finally reuniting with her child, Lilly calls out for her.