If she and her Pokémon finish that off, then...
...everyone else will have to go to the kitchen and get their own food instead of yummy leftovers! The horror!
EDIT:
Since you've got an NPC to explain things now, no harm in posting this reminder -
Time Flute - Trainer-useable item (not a Held Item). Has between 1 - 10 charges. Will instantly de-Shadow 1 Pokemon per charge, after which point it falls apart.
An ancient instrument, made of fragile materials. It has a beautiful, uplifting sound.