Answer:
Them
Explanation:
The pronoun that best completes the sentence is an object pronoun. Object pronouns are the ones that receive the action instead of doing the action (me, us, you, it, them, her and his). The ones that do the action are called subject pronouns (I, we, he, she, it, you, they).
We can also identify object pronouns in a sentence because they are often followed by a preposition.
Therefore, the one that best fits in the sentence is "them" as it is an object pronoun (just like "him" is), it is followed by a preposition ("with), and because it is not doing the main action which is to "go" but receiving the action.
