Unfortunately for you the vendor is gone (the last day was the 20th as marked on the turn in vendor reward screen). Those drops are gone. Sorry.
Used to be they hung around for a couple days or so after the event, but now only for so many hours. Always turn in my drops a few days ahead of time now. Never know for sure when the vendor will disappear for good. Maybe in the future, they will disappear the second the event ends. Personally don’t understand this logic. Think giving players a week or so to turn in drops would be what most other games would do. But this is UO.
Yep it a pain !, I recently found a chest full of eggs I had forgot I had