Fuck me! My ILs wouldn't be that bad, but my mum on the other hand... I live on the other side of the World from her, and sometimes even that's not far enough.
you need a plan, ASAP. Here are some suggestions:
When you know they are going to be around to supervise the house renovation, pay some shady guys to come to your house naked. Parade them in your garden. Mention casually that your DH and you like orgies, didn't they know, and encourage them to join if they want.
Show extreme enthusiasm that they are now going to live next door and can take care of your children during your 6-month volunteering project in Nepal. Which you plan to make a yearly thing.
Casually drop into conversation that your children have started learning the drums, recorder and violin and the window of the music room leads directly into their bedroom. Tell them the kids are looking forward to showing their emerging musical skills to their grandparents. Every evening.
Borrow some yappy dogs from some neighbours/friends and have them in your garden when they're around. Make sure some dog shit is evident on their side of the house.
Tell them their garden is situated over an ancient Celtic burial ground. It is said the soil is cursed. Several neighbours have died in the past under suspicious circumstancves. Human bones were found after the last neighbour moved out. But tell them to not worry, it's surely just an urban legend.
You're still in time for them to use the house next door as a rental!