You have to see if the sentences are singular or plural nouns

the family (is, are) going on vacation to georgia

the school staff worked throughout the summer on (its, their) lesson plan

that group of spectators (is, are) getting awfully rowdy

the set of books fell from their shelf

the audience (is, are) returning to (its, their) cars

the staff (was, were) very happy about (its, their) bonuses