C) He invades England Tudor-style and kills Richard (if the scenario plays out the same with the princes in the tower) and marries either Elizabeth of York or some other daughter of Edward IV to shore up his english support. I can see Tudor being a important player in his attempts or reign.
The existence of a real Lancastrian claimant on the continent might have a major effect on the motivations of several important figures in 1483, so there's no guarantee Richard's usurpation and/or reign would go down the same as IOTL.
But his Edward IV's brothers weren't so lucky with progeny -George of Clarence had only two children, and Richard of Gloucester had one sickly boy.
You can probably infer the problem was with Anne there, though, given Richard had 2-3 bastards born whilst he was still a teenager.