I mentioned this in the update thread, but here is what's worth repeating.
Dadi isn't the only one responsible for Sudha's misery - Deepu is as well, and actually, so is Padma, since she consistently took Dadi's side over Sudha. For instance, in her recollections, Sudha threatened to complain to Padma about how Dadi treated her. How many times does anyone recall Padma criticizing Dadi over this, except after Jyoti left, and that too in a self serving attempt to deflect criticism that she was responsible for all the misery in the household? So while Dadi and Deepu were outright hostile, Padma always took Deepu's side over Sudha's, and did not oppose Dadi whenever she berated Sudha.
For instance, the night that Devika and Uday had their ice-cream date, he gave her a friendship card and then proposed, and she spurned him, remember what caused that? Sudha had brought home a more expensive tiffin, and was lambasted by both Dadi and Padma, and that night, reeling from that attack, she turned into Devika, went to the club, and was re-directed to Uday's home. That was also the night that Devika confronted Dadi and intercepted her hand as she threatened to slap her.
I agree w/ SammyGone above - if Dadi leaving is a solution, so is Deepu leaving, and we all know how likely that one is. In that household, 3 of the 4 people remaining haunt Sudha, even though 2 of them are now supportive. So if Sudha is to lay to rest Devika, she has to leave that place for good. That's why I'm hoping that she marries soon - she can't be a guest in the Vashisth mansion indefinitely. Once she marries Uday, that's her home, and family.
Looking at the Navratri clips, I was somewhat disappointed that Deepu was invited to the celebrations as well. What I hope happens next week - Sudha remains w/ the Vashisths for the time being and helps w/ the Navratri celebrations, and after that, Uday resumes dating her, and quickly proposes. I also think that when time comes, it would be good for Sudha if only KK was there at her wedding, but not Dadi, Deepu and definitely not Padma.