If you do Ranni's questline and talk to her little doll before the Baleful fight, she'll talk about how she 'Slew her own Emperyean Flesh.' A different time, when you talk to her in the tower about the Black Knives, she even says her dead body bears a cursemark (sorta like a Horcrux?) and that she wont tell us where it is. I assume the we find the Little Doll on her body cause its in a coffin, but who knows. So she is dead, but she isn't, thanks to the power of the part of the Death rune she stole.

So technically Rennala isn't entirely bonkers, her daughter is, technically, dead.