Activation Lock
So I have an old iPhone which I used it long time ago, but now I just wanted to open it. So I tried opening it, but I forget the passcode so I used iTunes for restoring it and successfully done restoring, but now after fresh starting, it is asking for an activation lock which I didn't know, as my aunt gifted me the mobile and she is no more now, so I didn't know the user id and passcode. I even tried with the IMEI number but the owner's name is also different, so could anyone guide me on this topic and help me unlock it?
iPhone 5s