Canola oil is vegetable oil.
There are many different types of vegetable oil, canola being one of them. Peanut, olive, corn, sunflower, safflower are other types.
Vegetable oil is just oil made from a vegetable, rather than an animal source.
I too usually only have olive and peanut on hand. I consider both to be fairly strong tasting, as opposed to the neutral flavor of canola or safflower. I used peanut in a cake the other day to avoid going to the store and it was fine, but you could discern the peanut taste.