preserving dehydrated foods prepared with citric acid, honey or syrup
Using a vacuum sealer before freezing should generally improve lifetime in the freezer. Note that this lifetime is all about quality; safety-wise, everything lasts forever in the freezer.

When food is frozen, the main thing that keeps it from lasting forever is interaction with the air, and it only reduces quality. As time goes on, water and flavors escape from the food, flavors from the freezer enter the food, and frost accumulates on the surface. (In the case of dehydrated food, water entering the food might actually be a problem.) If the food has been vacuum-sealed first, then there's no way for any of this to happen. This is why you can find things like individually vacuum-sealed frozen fish fillets - the quality is much better. So if your vacuum-sealing is good, your food should hopefully last as long as you want it to in the freezer.