Cynoff WP has been discontinued by the manufacturer.
A product that is labeled to be used in your lawn for hornets and wasps is Bifen I/T. It can be broadcast across the lawn as well as used inside around the cracks and crevices as well.
Yes, you can mix 1 level scoop of Cynoff with 3 to 8 ml of Nyguard into one gallon of water.
The red worms would actually have to come in contact with the Cynoff Wp for it to kill them.