Lice Treatments like shampoos and washes don't work anymore (especially if you have a lot of hair or thick hair)...lice have become immune to the chemicals. I'd try the mayo and if that doesn't help try vinegar too... you'll have to look up the right vinegar to buy. If all else fails, look into lice clinics near by, I wouldn't be surprised if there's one in or close to Philadelphia considering it's a bigger city. Theres a clinic in Buffalo here in NY called "Naughty Nits" that professionally removes lice, nits, and eggs from hair with 2 treatments. It's not the cheapest but it works. I had to deal with lice a few years ago (picked it up from a coworker) and I tried everything but nothing worked and I dealt with it for 6 MONTHS! it was awful. Then I found out about Naughty Nits and boom, gone within 2 weeks. You'll definitely want to bag up all laundry bedding and anything else the lice may have come in contact with recently and wash it all on hot water.

Lather the scalp in mayo. Its much safer than the lice treatment and will kill everything.

Buy a lice treatment shampoo. After you wash with it you’ll have to pick out all the lice & eggs completely. Then re-treat with the shampoo a week later. Comb through again.