I went on a 28 mile ride with a few experienced riders and a majority of riders who had not ridden a bike for years (like 15+). I was the youngest rider at 36 and the oldest rider was 72.
When we pulled in to the halfway point for lunch, there was quite an assortment of food. Those of us who rode on a regular basis had the normal healthy fare - apples, dried fruit, granola, etc.
The others had a whole different picnic in mind. The FUNNIEST moment of the whole trip was when one man pulled a 16" salami from out of his jacket and a pocket knife from his jacket pocket. I spit my mouthful of water everywhere laughing. Completely unexpected!
Someone brought chips, someone brought cookies. We shared.
We ate whatever we wanted. We all survived. We had fun.
I would just worry about me and let the others concern themselves with their own food. Let her provide whatever she wants. Let them eat whatever they want. And have fun.