This is the “Story Wrap-Up” mission of the DLC, and can be either good or bad depending on your choices up above.

Kasumi is Dead¶

Let’s get the bad news out of the way: if you went with destroying Acadia at all, Kasumi will be dead and the job of going back to the Nakano Residence and informing her family is left up to you. Head back and report the bad news. You’ll complete the quest here but won’t get the reward you normally would, but you will be told to “Talk to Nick” and “Talk to Ellie” as MISC objectives.

Kasumi is Alive¶

Any ending that doesn’t involve Harbormen or perhaps you killing off Kasumi is - for that Nakano family - what you could call a happy ending. So as long as you didn’t destroy Acadia, this should be the ending you end up with. After “Cleansing the Land” or “Reformation” you can go talk to Kasumi after everything is wrapped up and she’ll feel like going home. You can convince her to stay in Acadia, but why spoil the happy ending?

Get Kasumi to head home, then fast travel back to the Nakano Residence to witness the reunion. Kenji and his wife are very thankful, and offer Grandpa’s stash as a reward. The quest will officially complete now, but you’ll get “Dig up the Stash of Supplies”, “Talk to Nick” and “Talk to Ellie” all as MISC objectives. The stash is near the boathouse. Just follow the marker and dig it up, then open the Steamer Trunk. You’ll get a lot of bottlecaps, some ammo, and the unique weapon “Resolute Powerful Assault Rifle” , which has the modifier “Time slows down for a moment when chambering the final round in the magazine” on it. You can mod this thing a ton too.

And that, ladies and gentleman, is the main story for Far Harbor all wrapped up.