unlock an iphone

To remove the activation lock you will need to have the Apple ID/Password of the rightful owner of the iPad unless there are extenuating circumstances, You do have such circumstances. You likely inherited it. You will need to get proof of death and of your subsequent ownership of the iPhone and submit these items to Apple support. Apple, at its discretion may remove the activation lock. I suggest you choose from these support options.

Get a call from Apple support to help solve your problem using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and

region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help  https://getsupport.apple.com/. Go

through the options to find the best support option.

How to request access to a deceased family member's Apple accounts - Apple Support.