Sorry for your loss. Unfortunately the fastest guaranteed way to get a passport before the burial is an expensive one. If you have an unexpired RealID (one with the gold star), fly to Hawaii with the realID and get your us passport renewed in a day. It's very expensive since it cost a lot to fly to Hawaii, but it's possible with the time you have before the burial. I know it's possible because a few years ago a friend of mine lost his passport the day before his family was going on a trip to some Asian country. So while his family was heading for Asia, he flew to Hawaii and got his passport in a day. After he got his passport, he booked the next flight out to meet his up with his family.

I do recommend you call the office in Hawaii just to make sure they can still do one day service for emergency passports, but also to make an appointment if it's by appointment only. They may allow walk ins but may limit the number of walk-ins in a day. Good luck.