Now I'm trying to imagine a scenario where almost everyone is dead by the time you have the party in Citadel.
You'd have to kill Wrex on Virmire, kill off the entire crew during the suicide mission aside from Mordin and Thane then have those two sacrifice themselves during the events of ME3 as usual and then kill Ashley/Kaidan as well when they protect the council.
That leaves... Liara, EDI, Vega, Cortez, Traynor and Joker left for the party... er, small gathering *looks around*
Oh, and then by the end of the game you can have such a low EMS that you can take Liara and Vega along, get them killed by Harbinger then choose the Destroy ending and kill off EDI... oh, and not install the EC to make sure the Normandy is stranded with no hope on that unknown planet... or does the Normandy get incinerated by the red space magic blast with a low EMS? Either way... no one survives.