Rule of thumb: Opt for a gift that the host won't feel obligated to serve.
My Mama always said: Never show up empty-handed.
What not to bring: You bring a bouquet of flowers without a vase, the the host has to figure what to put them in. Wine is a common gift idea. If it's chilled then they feel they have to serve it & it doesn't compliment the meal.
Think outside the box. If they like wine, this wooden puzzle would be great! 
Opt to bring a gift that the host can enjoy after guests have left.
When the host says not to bring anything, a happy treat is always polite.