She (https://goldengirls.fandom.com/wiki/Eleanor#:~:text=Eleanor%20Grisanti%20was%20Sophia's%20late,to%20a%20young%20adult%20Dorothy).) was dying back in the old country (https://goldengirls.fandom.com/wiki/My_Brother,_My_Father), yet in another episode, it's mentioned that she and her mother made the boat trip to America. Her mother also popped up (https://www.reddit.com/r/theGoldenGirls/comments/p8bwul/episode_discussion_s3_e25_mothers_day/) in a 1950s flashback in Brooklyn (https://frockflicks.com/tbt-the-golden-girls/).

In one of the dumbest lines in the series, right up there with Rose saying Gunther and Alma Nylund (not Lindstrom) were her adoptive parents, Dorothy said her grandmother was 94 when she was 6. Clearly an exaggeration but an odd one to be sure.
I always regarded Sophia's mother moving in with her and Sal as canon. I figured she died sometime in the late 1950s or early 1960s.