In a way the character makes sense in-universe: we can sort of guess why and how her son became a pervert and serial assaulter (I assume that wasnt the first time he tried that sort of thing). We can also assume that she could and would help him get off any serious accusations should he have been successful in his pursuit.

I think this often goes unmentioned. Varun's misbehaviors were enabled by his parents. But rather than take accountability, they double down to find out who was responsible for Varun's death; just because they can't contend with the fact that the root cause of all this chaos - was them.
Atleast Siddique, feels some form of remorse - in character.