1) GET A PROFESSIONAL! No offense, I am sure your wife is doing a great job, but if she misses one nit when she is combing, the whole problem starts again. My children have had lice, the rule is I try combing, if I still find after the third day, I go to a professional. It is expensive but it's worth it.
2) Precaution - I am sure you COMBED the rest of your children (checking is not enough this is too catchy), changed the linen, towels, bagged the brushes, washed and dryed her coat. Anything that came in contact with the hair(Nits do not die in water so washing machine is not enough).....Yes, it is a big job, but this is how you get rid of it.
3) you must call the school or playgroup and make sure that the whole class is checked PROFESSIONALLY.