I think buying your food at MEC is a great idea - they have a variety of options for dehydrated food, plus a range of granola bars, energy bars, chocolate, drink mixes and even basics like freeze dried chicken. Check out their website to get an idea. In Vancouver, there's also a plethora of heath food stores that would have food & bulk items, plus Bulk Barn (for bulk items like nuts, dried fruits, chocolate, trail mix, pancake mix) and most grocery stores have bulk item aisles.
In general, the rules for bringing foods in from the US to Canada are quite different from the rules applied to any other country. Those rules allow many meats & produce, so long as the meat/produce is grown/raised in the US.
For food items from any other country, the rules is basically no meat, no fruits, no veggies. Doesn't matter whether it's fresh, frozen, dried or dehydrated. There are a few exceptions, but the rules change frequently depending on specific risks/seasons/threats, so it can be tricky to know exact what's legal and in what quantities.
It's not only fresh stuff that can be an issue - even items like rice or certain nuts, from certain countries, can be forbidden because of the risk of importing plant diseases and/or insects.
Granola bars are certainly food - they just generally aren't something you have to declare as per the food list on the customs form. Though, technically, if they contain any seeds, you should declare.
Also important to realize that processed and/or packages is definitely not synonomous with safe. Plenty of processed foods can still harbor pathogen bacteria/viruses and even insects. And certainly packaged foods can contain all of the above - think weevils in flour, bugs in rice (I've seen packages of rice teeming with insects in a grocery story.. ugh....)