Given that Judy has taken Sarah Palmer - and given her level of power - it’s safe to assume that whatever it was the Hawk heard in the back of the Palmer house was another of these entities. Based on the ending of Part 18, with the Palmer house being occupied at one time by the Chalfonts and currently the Tremonds - both Lodge entities - shows the expanse of influence Judy has. If Cooper and Laura are in the past, it shows us how long the Palmer family has been moved around as chess pieces; if it’s the future, then it’s clear that Judy has taken the house as a prize. Nothing these entities do, especially in the case of the Palmers, is done on accident.
In Part 8, we learn that the Fireman and Señorita Dido created Laura Palmer after witnessing Judy creating BOB. Naturally, we focused on BOB; his possession of Leland Palmer and his obsession with destroying Laura added to the Möbius strip of violence and suffering that is BOB’s interaction with the Palmer family. Instead, it’s clear now that their intention was for Laura to be the light to fight the darkness of Judy. This point is driven home in Part 1 when Laura removes her face revealing a pure, white light juxtaposed against Sarah removing her face in Part 14, revealing a black void.
Adding both Judy and Sarah Palmer not only brings in a generational aspect to the battle—after all, good and evil is an endless battle—but it makes the struggle a matter of family. And, of course, by possessing Sarah, Judy defiles the one final member of the Palmer family while adding a kind of spiteful irony to the proceedings. Sarah once birthed Laura, the vessel of light, and she herself was now a vessel for the Mother of Evil. To fight Judy, Laura would have to fight her own mother. Wearing Sarah’s skin, Judy could claim in a roundabout way that she was Laura’s mother. Again, it adds to that cyclicality of good and evil. One can’t exist without the other and one demands the existence of the other. They are connected like a family.
This ties into the end of the series. Judy, using Sarah’s voice, whispers Laura’s name, apparently knocking Laura out of her Carrie Page delusion. The truth strikes her like a hammer: her trauma can never be erased. Pure evil cannot be ignored, only confronted. The sacrifice of fighting the battle against evil is the innocence of those who are fighting it. Cooper and Laura, caught in this cycle—where they see themselves repeatedly changed at the character level (living as Richard, Dougie, Mr. C or Carrie Page) is a metaphor for the loss of that innocence and the changes that can happen once darkness becomes known and confronted. Judy was never defeated in the series because she never can be. Cooper and Laura are never truly gone because they can’t be either. They are the balancing scales of the forces of existence.