- “This was a good breakfast, Beth. You really made the crap out of those eggs. I wish your mother was here to eat them.”
- —Rick referring to his wife.[src]
Mrs. Sanchez is the ex-wife of Rick Sanchez, the mother of Beth, the mother-in-law of Jerry and the maternal grandmother of Summer and Morty Smith. Her real name is unknown and she has never physically appeared, but she is the woman whom Rick left before he moved back in with his daughter twenty years later. She has only been brought up few times, by Rick and Beth only, and very little is known about her.
In the pilot episode, the first mention of Mrs. Sanchez happens, when Rick says "This was a good breakfast, Beth. You really made the crap out of those eggs. I wish your mother was here to eat them." This comment was so nice, it brought a tear to Beth's eye.
It is hinted by the scene from the pilot, that Rick's wife is deceased, but this is dissolved in Rick Potion #9, when Beth reveals that Rick left his wife, as well as Rick saying that "Love is just a chemical reaction that compels animals to breed" before mentioning that he was also part of a failing marriage, much like his daughter and son-in-law. He then encourages Morty to break the cycle and focus on science.
In Auto Erotic Assimilation, Beth tells Rick that "I can't sacrifice this whole family's safety just because I'm afraid you'll leave again," noting that in saying this she sounds like her mother. This seems to indicate that Rick left his wife because he placed the importance of his experiments over the safety of his family. It's possible that she is still alive but doesn't come around much and it's still possible she might make an appearance in the show.
In The Rickshank Rickdemption, Cornvelious Daniel, an agent from the Galactic Federation, went into Rick's memories, via brian-link, to retrive the origin story of Rick becoming a criminal. He found the memory of Diane Sanchez, who was very clearly the wife of Rick and biological mother of Beth. Diane died, when one of Rick's inventions exploded, leaving behind only himself and Beth, and leaving Rick to raise Beth on his own. However, instantly after this, Rick revealed that this whole story was a completely fabricated story he quickly thought up, just to trick Cornvelious Daniel into giving the Brainalizer a virus, making it unlikely that Mrs. Sanchez was the woman, portrayed in the story.