I think when Tulsi comes back into Shantinikaten... Mandara will also come back
now obosley Bhoomi n Manthan will hate Tulsi so Mandara will come and will tell Bhoomi that She is her accual Grandmother.. and than Bhoomi will want to go to her and where ever Bhoomi is Manthan will want to be there too and Karan wouldn't be able to say no to his kids.
Thats my predection what do you think?