I read that Maya continued to serve as overseer of the treasury under Horemheb. He oversaw building projects in karnak also. He died about nine years into Hormheb's reign and his wife Meryt took over his job.
His tomb wasn't discovered until 1987. It was located in Saqqara near Horemheb's original tomb.
Nakhtmin is a mystery and his fate is not set in stone.
I don't believe his tomb has ever been found, that I know of.
Most Egyptologist presume him dead around the time Ay died
Foul play for the throne most likely involved.