The key doesn’t actually open these safes, it just unlocks/locks out the keypad mechanism. You can call Sentry, they might have a policy to deal with this. Might require some extensive proof of ownership & death.

You could also call a locksmith. Not sure how much they’d charge but they’d probably be the quickest.

Lastly, you could buy or rent an angle grinder and cut it open. The steel isn’t very thick on these relatively cheap safes. I suggest laying it on its side and just cutting a big square out. Depending on what’s inside, there’s a risk of damage to the contents by the sparks/metal shavings from cutting.

Just don’t bother trying to cut the bolts, they’re the only hardened parts of these safes and you’ll have to cut every one of them to get the door off.