I saw in my friends list that the prompt at
open_on_sunday was Pat, and had a plot bunny for it!
Title The Price to be Paid
After Buffy had run away, Joyce had become involved in activities. She made a friend, Pat, who listened to her woes. Pat was her first friend in Sunnydale since she arrived, she offered a shoulder to cry on, and listened to her worries about her daughter, divorce and Hank.
While she worried about Buffy, she drew strength from Pat.
When Buffy came back, they had a party, Joyce was so relieved to see her daughter.
The party was invaded by Zombies, and Pat had died.
Joyce knew that was the price to be paid for her daughter being The Slayer.