Forgotten Verification Details - Can't log into icloud or iPad

I logged into my dad's old ipad yesterday -no problem, and managed to retrieve some lovely photos and family videos. He died a few years ago so, it was really nice to look back on some memories.

I was trying to transsfer the photos to my iMac and attached the cable. No problem there - just clicked the tabs asking 'do you trust this ipad'. It didn't seem that straightforward to transfer the photos so I disconnected to ipad and tried to figure out another way to transfer photo folders via icloud and photo sharing.

-That didn't seem so straight forward either. So I reconnected the iPad to the iMac ....this time iTunes started to open by itself. The screen blacked out on the iPad and I was asked extra security questions and verification to unlock it.

-Im pretty sure I have the old password(s) he used correct. The answers to the security questions ...not sure about.

And then the other option .... to have an email sent to his registered (recovery) email .... well it's his i- cloud email, and ....I can't access that email without the answers to verification questions ... so I'm kind of stuck here!

So, Im wondering is there any way I can solve this.

Any help would be much appreciated!