Can owner take "reasonable" time to refund security deposit?

My tenant in Bengaluru pays his rent and maintenance on time. However, for other reasons, primarily based on his attitude in working with us, which makes us nervous, we have asked him to vacate with 2 months notice (2 months notice on either party is mentioned clearly in our agreement). The tenant has agreed to vacate in 2 months and has sent us an email to that effect. After a few days, he followed up with another email that had a threatening tone: He says it is his duty to inform prospective tenants regarding a previous dispute (which we actually finally settled in his favour) and also says that he needs every penny of his security deposit back on the day that he vacates and otherwise, he would hold on to a key. Our agreement clearly stipulates that once he hands over peaceful possession before the end of the notice period, we need a reasonable amount of time to inspect the apartment and assess damages if any in order to determine deductions from the deposit, if any. Within reason, we always need a week or two after the tenant vacates to get quotes for damages. Can the clause above in my agreement be enforced effectively, and how do I deal with this tenant and ensure peaceful transfer of property?