How can I access my deceased mother's iCloud account?

I'm trying to get into my mums account. She died a few years ago but my dad has been using an old ipad htat was registered to her. He forgot the PIN and has managed to lock it.

Added to that, no one can remember her security questions so her account is locked too & since she added her icloud account as the login and registered account - we can't do a reset by email either.

The apple website just sends me round in circles and although not worried about a 10 year old ipad, we would like to get any pictures off her icloud account that we might have forgotten to copy off.

Is there ANY way to get apple to help reset the account so we can access it on icloud?

[Re-Titled by Moderator]

Original Title: Security Questions - Dead Parent