singular word. so you’d either have to say “the family needs to work on its anger issues” or if that sounds kind of strange to you, to refer to people as “it,” you can say “the family members need to work on their anger issues.” in this case you’re using a plural noun and a plural pronoun. so whatever noun or pronoun you do use, you just have to make sure they agree.
as you’re writing, you also want to remember that the number of your nouns and the pronouns that refer to them should also agree when you’re writing sentences. so, if you have a word that you are replacing 