Yes, Kusum should fight back. But what we don't realize is that women in rural households, and even in towns and cities often do not have the means to fight back. Imarati has a very dominant personality whereas Kusum is meek and mild. She has probably been taught to adjust in her sasural all her life (as our girls are. Girls should never speak loudly, girls should never assert themselves, girls should be meek like lambs and adjust to every demands in the sasural and become adarsh bahoos...blah blah blah). If she stands up to Imarati and gets thrown out, where will she go? She is not self-sufficient, her maike is probably poor and won't take her back and everybody will blame
her for disrespecting her saas. (There are instances where even educated, earning daughters-in-laws can't speak out against domestic abuse because they have been brought up that way. And I speak from experience) Imarati has even taken away her son's love. It's easy to manipulate kids, isn't it? Because a true, loving parent needs to be strict and loving equally and the kid doesn't understand that the strictness is needed for his own future, and here we have a selfish grandmother who is prepared to ruin the boy's life by letting him do whatever he likes as long as he thinks his mother to be his enemy and hates her.
Her husband isn't there to support her, and even if was, would it really matter? Look at Ved. He is there. He knows the whole story of how Imarati pre-planned the whole break-up of Anuj and his girlfriend? Has he stopped worshipping his mother goddess? No. Did he as an elder brother at least try to reason with his mother for his brother's happiness? No. Sajni gets on one's nerves with her 'aap to mere nature janti hai' sometimes, but you can't help feeling sorry for her at times. She tries so hard to make her husband love her. Does Ved even understand that his wife is also a woman who may have feelings and expectations just as his mother does? That she also may get hurt? No.
Imarati's sons, her borther-in-law all think she is a Devi or something. What chances do Kusum and Sajni have against her?
You know, I'm sure Ambi will teach a lesson to Imarati, but I also think Maya could have taken her on too if she had married Anuj. She is independent, and she knows her mother will always support her. I think that is one of the reasons why Imarati didn't want her as a bahoo.