Haven’t personally tried but heard Malibu C Swimmers Wellness Remedy – is magic in a packet! Mix it with water, slap it on her hair for 5–10 minutes, and it is supposed to strip away that green.
A few home remedies you could try —
Baking Soda Paste – Mix baking soda with a little water, rub it on, wait 5 minutes, rinse.
Apple Cider Vinegar Rinse – Mix 1 part vinegar to 4 parts water, pour over her hair after shampooing, and rinse.
Tomato Juice or Ketchup – Coat her hair, cover with a shower cap for 20 minutes then rinse.