He loved her witch's costume.
3 seconds sound clip from the Halloweentown movie soundboard.
You can hear this line at 00:37:48.125 in the Blu-ray version of the movie.
Quote context
[...]
- Is there gonna be a Halloween party today, Grandma? Everybody's all dressed up.
- That's the way your mother ran into your father: by crashing a Halloween party!
- He loved her witch's costume.
- What are you so happy about? I thought you didn't want to come.
- I decided this really is a dream, so why worry?
- I like Halloweentown, but why do you have to live so far away, Grandma?
[...]