Answer:
Sebastian meets Feste, who mistakes him for Viola/Cesario
Olivia mistakenly thinks Sebastian is Cesario
Feste, disguised as Sir Topas, ridicules Malvolio in the dark cell
Sebastian thinks that he is suffering from memory loss or has gone mad
Olivia gets a priest and marries Sebastian, still thinking he is Cesario.
Step-by-step explanation:
Plato answers