There's a slight pause. She remembers what they said as she was trying to bring the mansion down on their head, about some people being happier here. She hadn't believed it at the time, but, well...

"... that must have been really hard on you guys. So, clearly we gotta make up for that by giving you the best New Years Eve ever," Katherine waves her hand, pint-sized fireworks popping off in the air her head. "It's the least I can do after - y'know, all that."