I can tell you what I'd do based on 8 years of combing out dsd's lice - and I can comb out hundreds at a sitting (she doesn't live with us btw!).
With so few I really wouldn't bother with any lotions or potions. I'd just comb out with loads of conditioner every 3 days for the next couple of weeks. The nitty gritty comb is the business.
If dd picks them up from dsd and I find, say half a dozen in her hair, I can normally get rid of them after a couple of sessions (but I always keep going every 3 days for a fortnight to make sure).
I definitely wouldn't bother boil washing bedding and clothes.
It might be worth checking everyone in the family.