Options are limited in Gruene. Mozie's is a good spot, as is Cantina del Rio. A breakfast burrito at Los Gallos is a must. Other than that, there are a lot of options in downtown New Braunfels. Go to Krause's and sit in the beer garden - they have a great beer selection and lots of German food options. Muck & Fuss is the burger spot. McAdoo's is a cool building with decent seafood options. Huisache Grill has an old Cafe Eccel vibe. Grab dessert at 2tarts Bakery.
Make the 5 minute drive to downtown NB, park, and spend a day walking around, drinking, and eating. There's a ton of fun stuff to do that's not just battling old people wandering aimlessly in Gruene.