Refund of Token Amount

Dear Sir, I have signed a MOU and paid a sum of Rs.1,00,000/- (Rupees One Lakh only) as a token amount to proposed seller against his flat three months back. I have withdrawn the deal for the following reasons: (i) The original owner of the Flat was one X. Mr. X died leaving behind Mrs. B (wife) (“Seller”), Mrs. C (daughter) and one son D as his legal heirs and representatives. (ii) On verification of the title documents, I requested the Seller to provide me latest legal heir ship certificate; or (ii) put her son and daughter as a confirming party to the sale deed; or (iii) give me the proper documents such as succession certificate or court order for the legal heirship. But, the Seller has informed me that, her son is not in touch with her for many years, and hence it is impossible to give any relevant documents/ papers such as succession certificate etc. Due to unsatisfactory title documents, I have withdrawn the above deal and requested her daughter several times over WhatsApp communication and also telephonic conversation (whose contact details provided me for the communication), to refund the above token amount Rs.1,00,000/- (Rupees One Lakh only). At present, I heard that the seller has sold the said Flat to another person and registered the flat with sub-registrar office. Could you please let me know is it possible to register the said Flat without legal heirship certificate? And also what are the legal procedures to get my advance amount of 1 lakh. Regards Jayanti