Answer: b. drove a wedge between people who once were friendly.
Explanation: In the given excerpt from the song “Brother, Can You Spare a Dime?” we can see that it emphasizes the idea that the problems of the Great Depression drove a wedge between people who once were friendly, this is expressed in the excerpt because the speaker is talking about how the other person used to be his friend, and he and other people, use to call him "Al" and now it isn't like that.