I had a friend when I was younger that her kids had it all the time. I would cover their heads in Mayo or Miracle Whip and then put a plastic bag over the hair for like 30 min. Then make sure to use a lice combe to get all the eggs from the hair. Especially around the nape of the neck and behind the ears. And wash and vacuum everything in your house very well.
I have 4 sisters we all had long hair as a children so lice was something we all knew the drill for. My mother used minersl oil and vinegar equal parts. She covered our heads in it and put .sn old pillow case on the pillow and we went to bed the next morning we got our hair comed in the morning and ten it was off to the shower with a bottle of dawn dish liquid. After that a week of lice combing and then 1 last treatment for good measure. The oil smothers them and the vinegar detaches the eggs from the hair folical...added bonus your hair feels nice and smooth for days!!