I cant figure out how to keep everyone alive on the last mission in M Effect 2?

my ship was fully upgraded so i didn't have to worry there I chose Tali as my vent crawler and Miranda as my first leader. Then I chose Miranda as my shield and Garris as my second leader (I didn't chose Jack as my shield because I lost her loyalty) and I chose Grunt as my escort. Legion got carried away by those bugs and after I was going back to the ship I saw Mordin's dead body and jack's dead body.