Can a token be returned to its owner's hand?

Tokens are a special type of permanent that can only exist on the battlefield (or briefly in other zones during certain state-based effects resolution). According to CR 111.2, a token that leaves the battlefield is put into the appropriate zone but ceases to exist the next time state-based actions are checked — or in the case of the hand or library, it simply never successfully arrives.

More specifically, CR 111.8 states that a token that leaves the battlefield cannot move to the hand or library. If an effect would return a token to its owner's hand (such as a bounce spell like Unsummon), the token leaves the battlefield and is placed in the hand zone momentarily, but state-based actions immediately cause it to cease to exist. It never actually 'resides' in the hand and cannot be played from there.

This is different from tokens going to the graveyard or exile — tokens do briefly enter those zones and can trigger "whenever a creature dies" effects, before ceasing to exist. However, the hand and library are special cases where the token simply disappears.

Concrete example: Your opponent controls a Goblin token and you cast Unsummon targeting it. The Goblin token leaves the battlefield and is moved to its owner's hand, but state-based actions immediately remove it from the game. Your opponent does not get a card in hand and cannot replay the token.