May should resign her position in favor of Nigel Farange , who could soon be Sir Nigel Farange.
She can't. He's not an MP, he's not running as an MP, and his name is Farage (not that that really matters but just for the record). She can't resign her position in his favour.
Theoretically he could take over, but he'd have to contest a by-election first - and then convince the Conservative Party to elect him leader (assuming they do win the election and take office).
At the moment, based on the polls, I do expect a Conservative victory, but the majority may be small enough (or there may be a hung Parliament) to make May's position untenable - a narrow win when you started the campaign looking at a landslide is not a good result - but she can't appoint an annointed successor. If she's out the Conservatives will choose somebody else and it's unlikely to be somebody who left the Conservative Party in 1992.