I will never know for certain but have reason to believe that the dead stick around as a whole soul or a ghost for a while, about a year or so (but possibly longer if they had unfinished business). I had two friends who died quite young (24 and 30) with both I felt their souls visit me soon after their death as well as a year later and since then their presence went quite. I also had meaningful dreams about them and made a space on my dia de los muertos altar with the hopes that praying for them would help them find some kind of peace and a happy transition to become whatever they will become after their farewell tour.