Thanks @Opus 17 that is very clear.
Sorry, I originally misunderstood the sentence in your previous message: "Alternately, they could issue a W-2C showing the revised (minus the payback) box 1 and box 16, but showing the original box 3-6" and I thought that you meant Boxes 3 & 5 should remain the same as the original W-2 issued to me (current W-2), i.e., remain reduced by $30K upon the bonus repayment.
Now, Option B makes perfect sense to me.
If I decide to file Form 843 do you know if I should file a separate Form 843 for Medicare and a separate one for Social Security? .. or I can just file one form as they are both FICA taxes? I wish the instructions here would be a bit more specific: https://www.irs.gov/instructions/i843
