+1 Flybye.

Many, if not most, people don't put that much thought into what they eat (including diabetics). You can encourage them to do so, especially for the ride, but to nag too much or come off as judgmental would be counterproductive. That said, I do believe encouraging the lady towards the idea of a post-ride feast would work out better for everyone.

Isn't an egg and mayo sandwich just egg salad?

mmmm, egg salad.
Karen