You have probably passed it.  Document retention policies are a mixture of compliance with statutory requirements, retention of documents until the statute of limitations has run on any likely claim, and personal and historical preference.  If no one has filed a claim against the foundation in the last 16 years, it is unlikely that any one could survive a defense of the statute of limitations.  (There might be an exception if you dealt with children for whom a statute of limitations does not start until they are 21 years old, but that seems very unlikely.) Assuming that you filed all of your required tax returns and didn’t commit fraud in the ones that you did file, the statute of limitations for the IRS has also expired many years ago.  It sounds as though there is no legal reason why you would need to save anything.

That’s where the personal and historical issues come into play.  If your foundation played a significant role in the community or your father was a revered figure, it might be nice to donate the documents to the local historical association or similar archival organization (if they have any interest in taking them).  If you or the next generation of your family has a historical interest in the foundation, you might want to save its governing documents, board minutes, financial statements and any other special documents that capture the essence of what it did.  But if you or they aren’t intending to write a family memoir and don’t feel the need to keep the actual records, you should probably get rid of them now.  It will be one less chore for your heirs when you pass on, and, even if they don’t know what you did, they will thank you for it.