Attached above is my custom report setup. Please help me to get closing balance in it
You will not be able to produce such a custom report. Closing balance (by which I assume you mean the balance of an account or the quantity of an item after the transaction) is not a variable Manager records for a transaction. And custom reports are based on transactions posted to ledgers.
Closing balance is the cumulative total from the start of your records until the closing date of interest.
So you need to change the start date.
To show period data you need two runs of the custom report.