Did she bequeath the iPad or the apps/data on the iPad and the iTunes account to go with it? I'm pretty sure that even if the device is locked, that you can still do a factory reset on it and then have access to the iPad. Granted you would lose all the apps and data on the device, but you would still have the device to use as you wish.
If she bequeathed the iTunes account, then the account email and password should have been in the will or related documents, if not, then it's reasonable to assume she just left the hardware which you can reset and then have full use of.
No, it was just the iPad.
The problem is that since iOS7, Apple implemented a kill switch called "Activation Lock" in an attempt to slow down the theft of the devices - with it, the owner can remotely wipe the device, and more importantly, that device cannot be used by anyone else, thus ensuring that any stolen iPads, iPhones, etc. are rendered worthless.
What likely happened is just that - the iPad got locked and is right now, effectively worthless.
Of course, Apple has to be careful too - they can't really offer a way to unlock those devices because it's really a backdoor to Activation Lock and a way for criminals to well, steal your device and then cry to Apple to unlock it saying it belonged to their parents so they could resell it as more than just scrap.
It's really one of those catch-22 situations - Apple can't contact the original owner to verify if that iPad really belongs to them and they're not just some criminal looking to change their $0 iPad into a $400 iPad on the stolen goods market. And they can't just take those documents because well, the family could come back again next week with another stolen iPad and do the same thing.
And no, Activation Lock is practically impossible to defeat - if you reset it, it'll ask for the Apple ID credentials before you can proceed. If you get an unlocked one and try to restore it (with Find my iThing on), iTunes refuses to do it until you turn it off (which requires the password). If you force DFU and reload, it won't work until you re=login again, etc.
It's one of those things - what can Apple do? Remember the goal is to make the illegally acquired resale value zero because a user buying it can't do anything with it. And any way for Apple to help this family can be exploited (hell, do you KNOW that the iPad they got bequeathed wasn't stolen?). Apple requiring a court order basically means the courts will have to ascertain the identity of everyone and be enough of a pain that even a thief probably won't go through that effort. Certainly not one who wants to be identified should the iThing really be stolen.
They may have a chain of evidence though - the store receipt where the iPad was purchased on a credit card, a credit card bill with the charge on it and the billing name and address which can be compared against their Apple ID account, a death certificate with the same name and address on it, a will with the same name and address, and the iPad, whose serial number will match that on the receipt. Woe be to those who bought it at a store who doesn't record serial numbers, though!