"GREY'S ANATOMY - ABC's ""Grey's Anatomy"" concludes the season with a two-hour shocker, THURSDAY, MAY 20. In the first hour, entitled ""Sanctuary"" (9:00-10:00 p.m., ET), Seattle Grace Hospital is hit with a crisis like no other in its history. Then, in the second hour, ""Death and All His Friends"" (10:00-11:00 p.m., ET), Cristina and Meredith's surgical skills are put to the ultimate test. (ABC/DANNY FELD)ELLEN POMPEO, SARAH DREW"