Termination of lease deed

Hi, I have a commercial space for which there was an interest from an Indian company to establish their operations. We have a MOU signed and initial token advance followed by 1 month advance when the MOU was signed followed by agreement on stamp paper. 4 months advance was paid by the tenant as part of agreement which was signed by us (landlord) and the tenant. As part of the agreement, we were to setup a commerical building as per their specifications and inline with the local government rules. We have followed both to the exact rules and specifications. 95% of the building is complete. The minimum lock-in is 24 months lease from their side and 10 years from our side. Now when the building is almost done and we are ready to send an email asking them to start their operations, they have come back saying they don't want to establish their operations. My questions are 1. Can I ask them to pay for the lock period of 24 months that they have committed to as per agreement on the stamp paper which was to be registered once the building is handed over? 2. Can I sue them for getting me into this agreement and backout at the last minute without a proper reason or justification? Appreciate your feedback and suggestions.