I had lice as a kid and what got rid of it completely for me would be a regular store bought lice treatment, comb out all eggs and dead lice, in 2 weeks do another lice treatment and comb them out again. Section hair, the eggs are mostly behind the ears and in the back of the head. Mayonnaise has been proven to not work. If you comb all the eggs out correctly you should be able to get rid of it fully after the second treatment.
I had lice and I took them out by combing consistently everyday, dyed and flat ironed my hair .
If you can get a prescription from the doctor for head lice treatment it works wonders! You have to make sure to put all stuffed animals in garbage bags and set them out somewhere for at least 2 weeks. Bedding wash on hot water setting and then put in dryer. You also need to get lice spray for furniture and mattresses. And then vacuum the beds. You have to do it daily (i did it twice a day).