Seller is delaying for property registration / Complete the deal

Hi We have purchased the flat in Thane (Mumbai) and have paid the token money INR 51000 in the month of Feb'20 & subsequently on 15th Feb'20 he transfered Rs. 7 Lacs to Seller bank account. On 6th March'20 we have paid the stamp duty and registration fees to the govenment and generate the challans. On 9th march we schedule the registration but due to some personal work we cancel the registration and reschedule the same on 14th March which was cancelled by the seller due to his personal reason. and thereafter due to lockdown we could not able to do the registration. From 1st June'20 registration offices are open hence we contacted to seller but he is not ready to come for registration due to fear of corona. Since last 1.5 month we are following up with him for registration but he is not ready to come. He is staying in the same area where registration office is located. (approx 300 mtr from registration office). we have not done MOU & token receipt as well. Now we want to cancel the deal & we want our money refund with interest if the seller is not ready to complete the deal on or before 14th August.20. Kindly advice. 1) Should we need to sign the MOU? 2) If we need to sign the MOU then what will be the conditions to be mention in MOU. Thanks in Advance