Evaan Verlaine (Canon) / Keyan Farlander (Legends)
It has been confirmed that the pilot who survived alongside Wedge and Luke was Evaan Verlaine. Per the Star Wars: Battles that Changed the Galaxy factbook
REBEL ALLIANCE: Of the thirty rebel
starfighter pilots who took part in the battle,
only three survived: Luke Skywalker, Wedge
Antilles, and Evaan Verlaine. The pilots’ sacrifice
saved all of the personnel on the ground and
secured the survival of the Rebellion.
We can also see this by a simple process of elimination from the Star Wars: Galactic Atlas factbook which shows that she was part of Gold Squadron piloting an Y-Wing. Of the named pilots, we saw all of the others (Dutch, Pops and Dex) killed on screen.
It was relayed by Steve Sansweet, former Head of Content/Fan Relations at Lucasfilm, in the "Ask the Jedi Council" feature on the old Starwars.com website that the identity of the Y-Wing pilot was canonically unknown but highly likely to be Keyan Farlander, a character introduced in the 1994 LucasArts game X-Wing.
Possibly of more interest is that other pilots survived, just off-screen.
Q. In Episode IV after the Battle of Yavin there are four ships: Luke and Wedge in their X-wings, Han in the Falcon, and a Y-wing
fighter. Who was in the remaining Y-wing ship?
A. It's pretty definite that more than just those four ships survived from the Alliance attack on the Death Star; others just
aren't visible on screen. The Y-wing pilot has never been definitively
identified. But, if you're the gambling kind, I'd say the smart money
is on Keyan Farlander, a starfighter pilot introduced in the original
X-wing game from LucasArts. Back in 1992, LucasArts published a
novella starring Farlander that came with some copies of the game. The
strategy guide for the game continues that story and places Farlander
aboard a Y-wing fighter during the final assault on the Death Star.
Farlander survives the battle, making him a good candidate for the Y-wing pilot seen at the end of the film.