Tulle Skirts

I wouldn't do a crop top, as some people may not be comfortable in that! Can you just have them wear any white shirt, or any white lace shirt if you want to be more specific?

View Quoted Comment That’s what I was thinking. So that’s why i’m in bit of need of suggestions.

If grandma is MOH you could get her a burgundy lace dress that matches the tulle skirts and have the bridesmaids do the tulle with a white lace top. If it's a less formal wedding you could even get away with white button up tops tucked into the tulle skirts. I think that would look better with longer tulle skirts or it might give a school girl look.
Crop tops don't flatter everyone and not everyone likes them, they can be harder to find in matching sizes if your girls wear a range of sizes.

I would put your grandma in something like the first picture, without the see through bottom of course. And then put your other girls in something like the other two options. I've also seen whole dresses that look similar that might be a good option for grandma.