Maire is pretty much right. I used to work in kids in a psychiatric hospital back in the day. The lice never stopped.
What I found is that it is treatable, however it needs to be done throughly otherwise it will have to be done again…. and again… and again. If there is a messy situation in the house adding professional assistance is good, because sometimes the family will be more responsive and the situation more seriously if it is someone who is not close to the family. The problem is some families can’t afford it.
I am not sure where the family that you are trying to help falls. If not treated properly and it is on going for a long period of time, I believe (but I am not certain) that lice can be classified as child abuse. That may be a way to “inspire” them. This maybe an opportunity to get them “excited” about getting things in order.
On a side note, the chemicals that you put on your hair for lice is really harsh & can be pricy. For children you can cover the hair shaft completely in mayo, put a shower cap on overnight & wash in the morning. This suffocates the lice. Repreat after eggs that were laid hatch. Mayo stinks, but that’s life.
I’m sure that there are lots of resources on the internet… but the things to keep in mind are … anything that touches their head or comes close to their head needs to be washed on hot or at least put in the dryer…. sheets, clothes, couch (steam clean or vacuum, then spray with lice treatment stuff), coat, car, etc.. My perfance to treat everything like it needs to be cleaned.
Things are that cleaned should be separated from things that aren’t – ie bag up all the stuff that needs to be washed, then keep all the clean stuff bagged as you treat the space.