Well…it’s certainly not what I anticipated, I was, going by the expression of what almost looked like disgust on her face expecting it to be a case of Lily being born that way or having an accident when she was young and her mom (in accordance to Canterlotian attitudes)not wanting a ‘broken’ child.
 
With what I now know, I can’t say that I still don’t want to give her a smack upside the head, but at least her motives are…misguided rather than malicious.

@MamasBabyDragon
 
oh, well at least she’s doing it on purpose. still not a good idea though.

@Brass Beau  
Not as far as I know, but it was an accident that happened while Lily was alone and unsupervised. Violet blames the accident entirely on herself, and convinces herself that she’d a bad mother.

@MamasBabyDragon  
Artist mention what that accident was?

@redweasel
 
According to the artist:
 

 
So yeah, as counter intuitive as it sounds, she’s sort of being mean on purpose so Lilian won’t miss her when they’re eventually separated. Not saying it’s right or wrong, but that’s her thinking.  
Violet’s father is in the hospital, so he can’t watch Lily at this time. The plan is once he’s out, they’ll move into his house, and he’ll be her guardian.  
And once again, Twilight ends up convincing Violet to be a better parent, and it would have ended in a warm and satisfying way.

@Background Pony #B2EE
 
well… regardless of who makes lilan’s mom stop wanting something other than motherhood, it’s still not right to leave lilian with her until she does. nobody should be raised by someone who doesn’t want to do it.

@redweasel  

 
According to blog’s author, it’s Twilight who eventually help Lilian’s Mom to accept her role and became a better parent. As for grandad, Lily’s Mom was just 16 when she had there so chances in this case grandad is not old, maybe 45 or something like this.

yeah, her mom is… not the person lillian needs her to be. either her mom doesn’t want to be a mother, or she’s going through some serious shit, so it’s good to get her and lilian separated. even if nothing else is wrong, if I was her mom, I’d always be reminded of what a sweet and kind pony lilian is, whose eye I destroyed when I failed to take care of her.
 
but… it’s always sad when grandparents have to raise a child. you’re less physically able at that age, needing more help yourself, and you’re not going to be around all that much longer.
 
I wonder if her mother has anyone to talk with about… her feelings toward lilian. that might be the best hope for this sorry situation.

someone get that poor child a better parent!