Medusa is only a character from myths of Greece, so she was not actually killed. In the myths, Perseus killed her and was said to have founded Mycenae. We can only find approximate dates for such fantasies. One of the seven sons of Perseus and Andromeda was Alcaeus whose son was Amphitryon the stepfather of Heracles. Heracles took Troy when Priam was a baby, and Priam was old when Troy fell again in 1184 B.C. tradition says.

We now have a definite date with which to work. We can estimate Heracles took Troy about 1244 B.C. and was in his prime then. His stepfather Amphitryon would have been in his prime about 1274 B.C. Alcaeus would have been in his prime about 1304 B.C. That gives us a date for Perseus to kill Medusa about 1334 B.C. Such calculations are just approximate, so the supposed date could be about 1364-1304 B.C.