I guess in one of the previous episodes it was mentioned that Goenka's removed Payal father n sister from the picture, i mean got them killed...But they didnt mention Payal Mother.
I have a feeling based on watching Revenge, that She is still alive probably left Payal n Nitya before Goenka goons attacked Payal family.
Also actress shown as payal mother doesnt seems like will play 2second role.