IMO, this is a patriarchal structure whereas the wife becomes a part of the husband's family, so it would fall on the mother-in-law to take on these responsibilities. The husband's family assumes the primary role in the couple's life. Additionally, it would fall on the MIL to properly care for and support the DIL during postpartum. This is part of their duty and expectation. Now, what happened here; I couldn't speak to why obviously the MIL and DIL didn't get along. Can someone please help me find an article somewhere that read that Naresh didn't approve of Mamta's Tiktoks? Maybe I'm dreaming but I thought I'd read it somewhere.
Mamta shared some reels with her MIL, they were more traditional, with lip-synching and singing, but still.
There are two parts here,
1) whether Naresh is the older brother - then by tradition, it falls on him to take care of the parents when they get old
2) as I have said, the "in-laws jokes" exist in every culture. In my own, it is mostly about SIL and his MIL. But realistically, the relationships between a DIL and MIL are more pregnant with problems, and again, it transcends all cultures.
No matter how difficult the relationship between a daughter and her mother might be, her children are your grandchildren; it is your daughter who is having birth pains, and the moment the grandchildren emerge, they are yours.
Not so with your sons. You raise these golden boys, you invest into them, they are "momma's boys", and then one day, they leave and go to another woman. And, they take care of her, and they tell you, "and my wife says that...", and what it begets is pure jealousy. It takes wisdom to tell yourself, "my son is happy with this woman. For him, for his happiness." It is a very old story and the only difference is that yes, in some cultures, the MIL holds more power.
I wonder there were more than obvious cultural issues. I was looking at Mamta's reels with Naresh and thinking that initially, at least, he did smile at her. He looked happy. I think that when his parents came for the first time, his mom noticed it. And all started from there. I don't know whether chhaupadi was merely a religious belief of the MIL, or whether she achieved more, separated the spouses physically, as Mamta ended up sleeping in the kitchen, or away with her friends. I wonder if menstrual issues were just a pretext. I wonder if she hated her DIL and if indeed, it is very unsafe to let her even be in the same country with her granddaughter.