Lily, Sirius, Prongs?
Lily was awake and alert immediately when the call came. They'd trained for this. She and James were on their way down to the 4th floor, where they were to be stationed, when she spotted Jamie and Sirius. They were battling Dementors already, and Sirius looked awful.
She didn't need Jamie to tell her he needed to get out of here, she just sent her own Patronus at the Dementors as James did the same, and together they got Sirius between them and down the stairs. He wouldn't be any use against the Dementors, but he could help them protect this floor, keep any Death Eaters from getting past them.