I vote (b) and (c).
How can believers respond when stories like this pop up in our world?
First, remember Jesus is, in fact, returning some day. I don’t know when He will come, but the Scriptures make it clear that He will return (1 Thess. 4:15, for example). We may disagree on the details of how His coming will unfold (pre-trib, pre-wrath, mid-trib, post-trib, premillenial, post millennial, amillenial, and the list goes on), but not on the fact of His coming!
Second, believing He will return should impact our living today. “But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be burned up. Therefore, since all these things will be dissolved, what manner of persons ought you to be in holy conduct and godliness” (2 Pet. 3:10-11). Knowing the end of the story should influence what we do while we are still someplace in the middle of the story!
Third, when people talk about Camping’s predictions, talk with them. Don’t ridicule Camping (I think plenty of others will take care of that), but instead ask questions about what they believe. Remember the movie, 2012? Not a great movie (I wouldn’t even rank it high enough to be a really bad movie!), but knowing that people went to the movie opened doors to talk with them about the future. Camping’s predictions can do the same. We can use false prophesies about the future to open doors to talk to people about the truth, especially when they start the conversation!