To be honest, Yoda's actions struck me as pretty much piss poor after the Clone War. He runs and HIDES! He does, as far as we know, NOTHING, for the twenty years it takes for Luke to grow up and come to him. Does he try to do anything to prevent the rise of the Sith? No. Does he organise any sort of underground, or even assist the Rebellion (Who could sorely use his skills and help no doubt) No. He sits in a swamp talking to himself.

Ben at least has the retconned in "Keeping an eye on Luke and keeping him safe" mission to carry out.