Indemnity bond for refunds

In response to petitions to Ombudsman for refunds for 6 to 13 years old return, concerned ITO has served me notice to file the Original IT Acknowledgement with tax challan/ TDS (in original) with B/S & P&L a/c and in Indemnity bond.

For HUF, do i file this bond individually ? Format thereof ? Requirements for notarisation ? How many bonds for six different assessment years ?

Details answer would be helpful ( Am 65 years old waiting for refund since upto 13 years). Thanks