So we never really heard anything about her mother. Who was she? What was her name? Why isn't she present in her family? Did she die in childbirth after Cassiopeia? Did she get killed during some assassination mission?
Why aren't there answers to these questions?!?! RIOT YOURE KILLING ME ;-;
Why did I get a downvote for asking a lore-related question inside the Story boards? What's going on here?
From the old JoJ issue #12, even if obsolete:
"Katarina and Cassiopeia are full-blooded sisters, and the General and his wife have been happily married (and faithful) to each other for nearly three decades. Katarina distinguished herself early as the tomboy of the family, embracing a military training regimen while she was still a child. Cassiopeia was noted for her enchanting beauty, and she took on an ambassadorial role until she was...changed. "
I've often thought she went insane after her beloved daughter turned into a snake. But that's just headcanon. There's no canon answer to these questions yet.
I really hope Riot has an upcoming Noxus Lore Event where these kinds of questions can be addressed. I would be very disappointed if they weren't.
My bets on, that either 
or 
killed her.
That's a nice catch! So we know she's not dead. Would still be nice to know her name and what her job was. Demacia has the traditional "women stay at home" culture; but given that Noxus is all about strength and that lets someone like Katarina become an assassin, I'm curious to know what her mother did for a living.
The answer is likely that their mother simply never played any important role,so we know nothing about her.
I mean we don't know anything about the parents of ~90% of the champions,so it is actually more surprsing that we know anything about Katarinas dad at all.
I get that not every aspect of the story will be explained in depth but a little back story would add so much life to the existing lore. We already know a lot about her dad, at least giving us her mother's name would be nice. Right now it just feels like she has disgraced the family or something because no one dares speak of her....
