Previous owner is dead and I can't reset iPad
I have an iPad that I am trying to set up for my Grandmother, which belonged to my recently deceased Grandfather. I followed instructions to reset it to factory settings but it says that I need to log in using his apple id. I know his email but I have no idea of his password. I have read that there is no way around this as you need the previous owner to remove it from his list of apple devices, but he is dead and cannot do that. Surely there must be some way to get around this, even if it involves going into a store with paperwork to prove this?
iPad, iOS 7.0.4