GREY'S ANATOMY - ABC's &quot;Grey's Anatomy&quot; concludes the season with a two-hour shocker, THURSDAY, MAY 20. In the first hour, entitled &quot;Sanctuary&quot; (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, &quot;Death and All His Friends&quot; (10:00-11:00 p.m., ET), Cristina and Meredith's surgical skills are put to the ultimate test. (ABC/SCOTT GARFIELD)ELLEN POMPEO