The correct answer and tone that Lorraine Hansberry conveys through Bobo's words "Man, Willy is gone" in the mentioned excerpt from A Raisin in the Sun (1959) is C. shock and disbelief because Willy has stolen his and Walter's money.
Willy, convined Walter and Bobo to become partners and invest in the liquor store plan. Since they do not have well-paying jobs, they have to invest their life savings. After making them think that opening a liquor store is a great idea, Willy disappears with all their money, leaving them completely bankrupt and devastating. In fact, Willy is only mentioned but does not even appear onstage during the play. That is why Bobo realizes that Willy is never going to show up and that they have lost all their money.