Basically there is nothing you can do if the creator does not fulfill the project rewards.
And in this case since the creator is deceased, the threat of not being allowed to do another campaign is useless.
Note that per https://help.kickstarter.com/hc/en-us/articles/115005126914-What-if-something-goes-wrong-after-a-project-is-successfully-funded-
"rewards are not guaranteed."
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