The best choice to make in this quest is to kill Rachel Lockwood especially if you are following The Board questline. You will receive more rewards when you kill Rachel Lockwood rather than sparing her in this quest.

What is the point of no return outer worlds?

Going to Tartarus is the point of no return, so if there's any side content you've left undone - now's the time to do it. Once you reach the prison, make your way through the complex until you come across Chairman Rockwell. He will confront you and your party, and you can either convince him to let you go or kill him.

Where is Rachel Lockwood on outer worlds?

Rachel Lockwood Location

She can be found in the Maintenance Tunnels beneath Prosperity Plaza at Byzantium.