Dementors are significantly slower than she is and cannot Apparate!

Focusing on murdering the Dementors does risk letting a lot of Voldemort's mortal allies escape, but, on the other hand, if she circles the castle and then wider grounds enough times, blasting silver fire, she can make quite a merry roast of what's at a minimum the vast majority of the Isles' (and possibly northern Europe's) horrible despair monsters. (The Thestrals help prevent the Dementors from fleeing anywhere it's slightly more complicated to roast them, like 'towards the Forbidden Forest' or 'towards Hogsmeade' or 'uncomfortably close to Hogwarts.')

These false Deaths have hurt her and hers, and she will not forgive them that. There will be time enough for the other minions later.

She eventually runs out of Dementors. The ones in visual range, at least.

None of them have escaped. A significant number of the mortal allies, especially those worse at Apparition, have joined the Dementors in Death.

They deserve it.

She lands in front of the castle's main gates.

Anathema gives Hogwarts its main doors back, and then proceeds to run out of them while shouting "Ellie!"

"Anathema!"

She slams into Ellie in a hug. "You're okay."

She's maybe crying.

Hug.

"I'm okay." Pat. "I'm okay."

She has had so many emotions recently and she is going to kiss her wife about them.

That sounds like a really really good idea.

There are people coming out to stare at the charred grounds so you know what, she's going to drag her wife away from anyone who wants to talk to them, they can send a Patronus or something to McGonagall -

And Fay's in the Chamber still, anyways. Anathema kinda had her knocked out until -

Until she was sure.

Yeah, Ellie should go... talk to her about that.

...Yeah.

To the Chamber, then, firmly sealing the tunnel behind them - to the side area Anathema had set up with an annoyed Scarlet watching Fay.

Scarlet thinks it is very important that Ellie know they were extremely worried, and Ellie should have considered the cat's feelings, too!

Sorry Scarlet. (Scritch scritch.) She doesn't think it's going to come up again, for what that's worth.

It better not.

Anathema nuzzles Ellie, gets them settled by Fay's unconscious form.

"...Are you ready to wake her?"

Deep breath.

"Yeah. Don't want to wait."

So she casts the reversal on Fay.

Who wakes up with a shuddering gasp. "Ellie - "

"I'm here, Fay, I'm right here." She grabs Fay's hands.

She pulls Ellie into her, hugging her.

"You - complete idiot - "

"B-big words from you..."

Sob. "Did - what happened - "

"Voldemort's dead. For good. He killed me and I saw my mom and she said I had mastered Death and I came back and bit him in half."