I am so jealous! Fall is my favorite time in the Jemez Mountains, although I hear an icy blast just came down from the Rockies. A few suggestions:
I agree with Bill - Los Ojos is a great spot, with good green chile cheeseburgers. An excellent place to get a beer, admire the Harleys parked outside and learn a little bit about taxidermy. Los Ojos is also a package store if you need a six pack for the campsite, but the grocery further south on Hwy. 4 is cheaper.
Also in Jemez Springs, you should try the Laughing Lizard Cafe. I am not sure about the hours, so call first. They have a little bit of everything: sandwiches, pizza, veggie burritos, daily specials (I had some good crab cakes there last year), wine/beer and truly transcendent pies. I once enjoyed a slice of the pinon, which was like a Southern-style pecan pie make with pine nuts. Appealed to my Arkansas and New Mexico roots simultaneously, which is quite a trick. I believe they also do breakfast, but haven't tried it.
Consettas, on the south end of town, is an Italian spot that also has daily specials and pizza. I haven't eaten dinner there in a few years, but did purchase an entire blackberry cobbler here last summer, made with freshly picked organic berries for a very reasonable price. The owner even sold us a pint of vanilla ice cream to go with it, and was extremely nice. Along with LL, they have many vegetarian/vegan items. Consetta's also has wi-fi, with the best reception sometimes found out back just outside the yurt that is behind the restaurant. I once had a paper deadline and sent it away while enjoying a cup of coffee here and looking at the side of Jemez Mountain. Almost made the deadline enjoyable.
Deb's Deli serves breakfast and lunch, as well as sodas and pies to go. I have only been there for breakfast, and while most of the things I have tried are just fine, their blue corn blueberry pancakes are very good, making the switch from a savory breakfast (my usual preference), to the sweet side an easy decision.
If you are coming go through Espanola on your way to Bandelier/Jemez Springs, El Paragua has some very greasy, VERY good tacos, and a lot of local, Northern New Mexico charm.
If you are coming from Albuquerque via Highway 4, there is a Blake's Lotaburger in Bernalillo if you need a green chile cheeseburger for the road, or if you are traveling on a weekend, pick up some food at the food stands just past Jemez Pueblo near the Walatowa gas station. Indian tacos and Indian bread are always available, or, if you are lucky, someone will have made Jemez enchiladas, which are a local specialty. They are made with flour tortillas, dipped in red chile, filled with cheese, and lightly fried so they are greasy, not crisp (in a good way). Continue on to Battleship Rock for a hike if you eat one of these - they are heavy duty.