Yes it can be a combination of both especially if the animal was very young and did not eat for that long.I really don't know what caused the dead tbh, would the mites have made him anaemic or caused him to lose a lot of blood?? Plus having no food, he would of been very week you would have thought? But he was exploring his cage most nights even up to his death. I would of thought he would of been very weak and never active, but that wasn't the case.
While a snake that is healthy and has a good body weight can spend months without food, it would not be true for a hatchlings that had mite issue on the top of it.
Ultimately no one can tell you for certain except your vet by doing a necropsy.
And in the future (if you get another animal) keep in mind that mite off does not work as it only treat the adult stage not the eggs, only PAM (Provent a mite) and similar product that treat all stages work.