But why were they attacking the neighbour in the first place? Wasps I have come across so far only seem to attack when their nest is under attack. Otherwise there is the sting you get only when one is trapped and suspects death imminently, or sleepy in the autumn. So, did he see some wasps and track them to their nest and start attacking them?
There are some pretty useful powders you can spray at the entrance and then they carry it in and it kills the whole nest.
I have dealt with quite a number of wasp nests over the years. Gown up, spray or puff and retreat before they realise anything is happening.
Richard, London, UK
If at first you don't succeed - pause, reflect, change something and try again.