Lease inforcement on move out without notice

[Daniel McCarthy]

One tenant of four on the lease moved in on Thursday and moved out Friday saying they did not feel safe in this Nashville  rental.The lease requires 30 day notice plus 3 months rent to terminate lease. I told them I would try to find a replacement if they give me a document signed by all to enter the property and show to potential renters. Any advice on how to handle and is the lease enforceable.