is there a store called Mariin's in Guernsey

No

Not that I'm aware of. They have a store but it sells their products.

Guernsey is a restaurant..and a dairy they sell there ice cream buy the scoop or buy the gallon i don't believe there store has a speart name .

I am not aware that the store has a separate name.

There is a store, they sell mostly Guernsey's products