Sushi is a food comprising many ingredients. It definitely contains rice, which is a grain. Usually it also contains seafood and sometimes various fruits or vegetables. Sea creatures are not vegetables. The typical makizushi type is wrapped in seaweed, which would be a vegetable.
Some of the ingredients are fruits and vegetables; some are not. However, even if everything in a piece of sushi was a fruit or a vegetable, sushi itself never would be. It is a combination of foods. It can never be a single fruit or vegetable itself. There is no plant that produces whole sushi naturally, so it is neither a fruit or vegetable.