Maybe it goes all the way back to when I first meet her at the base, got caught scanning some of the objects and had to take out the people there, but even so, it's strange to go from only talking till Ryder signaling the sniper to kill her, it's like it skipped a step or two in the convo O.o
Thats your answer if you kill every one on kadara you get the bad ending for this mission the way to go is scan no more than 2 o3 objects so pick well and speak with her son and then go to the tempest and develop a item to help the son walk again and then go to the nexus and talk to her it will give you the option to save her
