A "posthumous exhibition" refers to an art show or display of someone's work that takes place after they have died. It occurs to honor and showcase their creations after they are no longer alive. Full definition
«Dead Artists» Society» (a critique of posthumous exhibitions of Black artists» work), Art Monthly, London, Number 244, March 2001: 52 (eddiechambers.com)
Modern Art Oxford is currently presenting the first posthumous exhibition of works by Rose Finn - Kelcey (1945 — 2014). (artlyst.com)
Since her death, there have been dozens of major posthumous exhibitions in the United States and Europe, including at The Guggenheim Museum (1972), the San Francisco Museum of Modern Art (2002), The Drawing Center in New York (2006) and the Jewish Museum of New York (2006), and the Fundació Antoni Tàpies in Barcelona (2010). (dailyartfixx.com)