The Bride-To-Be

I would tell your fiance you don't want to get things off on the wrong foot with your future in-laws and that you understand he is not superclose with his parents, but is there something you could ask his mom to help you with that might make them feel included without making him uncomfortable.

Maybe she wants to help with the cake tasting or choosing flowers?

Hi Kish welcome  

Is  your mom wanting to be left out? or dont you get along well with her?

Talk to your Fiance tell him that you'd love his mom to help in someway, are you able to get your mom involved? It will be a great chance for both of them to be involved in something.

If it's possible host a meal for both familys in your home? It's a great time for both lots of parents to meet and gives you a chance to show them what you've both done so far for the wedding. Maybe they'll have ideas that neither of you have though of. 

Communication is the most important thing when planing a wedding

Let us know how things go