I sort of have a theory of what Meneka's raaz could be.
As we all know, Surya married Meneka only after the doctor advised Savitri not to have any more children.
Who knows, the next one could've been a boy, right?
So maybe Meneka wanted to be a Garodia bahu, and live like royalty and rule the house
So she paid the doctor to tell the family that Savitri shoulde't have children, so that Surya would go out and get married to her
It sounds a little ridiculous, but I think it could be possible
Yuks