In Final Fantasy X, as the story progresses we learn a lot about Yuna's father in his pilgrimage with Tidus's father and Auron; however, in my playthroughs (only twice), I've learned nothing about Yuna's mother except
her heritage and connections to the Al Bhed.
Is there anything in canon that describes the fate of Yuna's mother?
I'm still searching for an exact quote/transcript, but Final Fantasy Wikia matches my recollection of a conversation you can have with Cid on the Highbridge.
The backstory is not well fleshed out. There are no animations or cut-scenes - just a few passing mentions.
Yuna was born in Bevelle to a Yevonite father, Braska, and an unnamed Al Bhed mother. Yuna was four years old when her mother was killed in an attack from Sin during her travels to the Al Bhed Home, with the intention to repair her relationship with her brother, Cid. Her death established Braska's resolve to become a summoner and defeat Sin.
