Confirm identity for elderly relative in a care home?

My elderly mother has dementia and has lived in a care home for 18 months. I have had power of attorney for her for five years. She has no valid passport or driving licence and no longer receives utility bills, nor does she have a credit card as she is unable to manage her own money. She has been assessed as lacking capacity to make decisions and as such I have been appointed to act as the executor of my step father's will on her behalf. In order to do this I need to transfer the title of his property to my mother's name - but cannot do so as I cannot supply the required identity documents as specified in the form ID1. What do I do please?

Carol - if it's simply a Q of how to have an identity verified then PG 67 explains how to do that using either form ID1 or ID3 - Evidence of identity (PG67) - GOV.UK