She knows Ishwari so well. It was very clear from Ishwari's reaction that she is not welcoming the marriage decision of Dev just with anyone. Once again strange mother I say. She is being way too selfish. She wants to hold onto Dev after her husband left her alone as her only anchor for life.
I am sure she would be the first one to react against Sona after Dev's attraction towards her would come out in the open. She might even be worst then Mami in this case. Poor Sona n yes poor Dev. They both would be suffering deeply but won't go against Ishwari's wish n happiness.
I hope Neha, Riya, Nikki and Natasha (If she to remain a +ve character in the show) would help Dev-Sona in such times.
Oh have I made you guys sad already, oops apologies, I am gonna stop before someone shouts at me like Dev did to his sisters yesterday.