If they're in the house they've found food, follow the trail, one end is at the food and the other is the nest. Remove the food. Mix vinegar and water 1:1 and spray the trail disrupting the scent. Spray the entry point(s) to the house and the door sills. Go back to the nest. If it's accessible knock the top off and pour at least one whole kettle of boiling water down it - objective is to kill the queen. If it's not accessible chop up one of more lemons and spread all round the nest. Repeat the lemons every 1-2 days.