posthumous query

I was wondering if anyone knew if this could be done on bank accounts that are closed and the holder no longer living. My dad had a terrible time with a few creditors - they would have been business accounts and personal accounts and though he tried he couldn't get out of some accounts to relieve my mum of the debt which she duly paid from his estate. He would have been so delighted to get the banks et al back as they had little or no compassion when he was ill. He died 4 years ago. my mum is coming to stay with me tomorrow so I could check she still has details of the accounts which accrued massive charges upon charges in the recession and never recovered.
Hopeful!