Marking A Column Based On Date In Another Column

I have a worksheet that keeps track of members for an organization. One column, let's call it B, notes the month when the members are due to renew their membership. Our organization requires that members be notified of pending renewals one month before, the month of, and one month after they're due to expire. Rather than having to re-sort the database every time I want to pull up this information, I'd like to create a second column, column C, that puts a character next to the names of members who are about to come do.

Ideally this character would change depending on what stage they are in the renewal process (a month before, month of, month after). Super ideally, if this is even possible in Excel, members who haven't renewed by the last month will automatically be moved to worksheet two, which contains recently lapsed members. What sort of code would I need to do this? I've tried googling for it, but I can't find quite what I'm looking for, and I have no script savvy whatsoever.