We had very good luck with Tea Tree oil. It wasn’t without picking out all the nits tho! I bought cheap dollar store shampoo and conditioner. Then bought a bottle of tea tree oil from WalMart (about $5).
Mix about 1/4 bottle of oil into the shampoo (28 oz). I also put several capfuls into the conditioner. This seems to keep the little buggers at away once you get your daughter’s hair picked through.
I use it every day, and when possible let it stay in hair for 30 minutes before washing. Good luck! (but only 10+ kids at home now)