i think she mightve be getting some money from her deceased husband's land and no wonder why bindu is after her...I might have missed something, but how has nirmala got so much money? She used to turn up at the thela in worn out thin saris.
I'm surprised Sarla's household manage to pay for food at all. Surely if shanti had enough money to feed and give expenses for both households, they would have been rich by now...