Jedi Bibliothek has found the titles of the last 5 episodes of Star Wars Rebels season 2 and the season ends on March 30th.
Episode 18 ‘Shroud of Darkness’ March 2
Episode 19 ‘The Forgotten Droid’ March 16
Episode 20 ‘The Mystery of Chopper Base’ March 23
Episode 21 and 22 ‘Twilight of the Apprentice’ Part 1 & 2 March 30
We can assume that the last two episodes are the confrontation between Ahsoka and Darth Vader and the episodes at the Sith Temple. ‘Shroud of Darkness’ could be the episode with Darth Maul or the episode with the Jedi Temple Guards. For the two others, I don’t really have a guess but episode 20 seems to be an episode with Chopper according to its title.