Kerry Hellman is the same age as Jesse and Lisa. Her family is not mentioned or shown.
At the beginning of the film, Kerry is talking to Lisa about if she likes Jesse. Later, she talks about Lisa's party and attends it. She witnesses the deaths at the party massacre caused by Freddy.
At the end of the film when she, Lisa and Jesse are talking on the bus, with her telling Jesse that it's all over, Freddy's gloved hand bursts through her chest killing her as Jesse and Lisa scream in terror. Her soul was absorbed by Freddy and was released when he was defeated by Alice in the 4th movie.