Depends how you define Horror. It's not horror in the supernatural sense (ghosts, vampires, living dead) It's a psychological "warped person" film, a bit like Psycho, or Misery.
In the film Whatever Happened to Baby Jane? the title role was played by Bette Davis.
http://www.script-o-rama.com/movie_scripts/w/what-ever-happened-to-baby-jane-script.html just found this,
No
Good Girls Don't--- - 2004 Whatever Happened to Jane's Baby 1-2 was released on: USA: 11 June 2004
how can you find the original script of I dream of Jeannie whatever happened to Baby Custer
Yes. It was made in 1991 and starred Lynn Redgrave as Baby Jane and Vanessa Redgrave as her sister Blanche.
The cast of Whatever Baby Wants - 2012 includes: Christina Isabella Mani as Jane
Jane
Baby Jane was Rod Stewart's sixth UK number one hit in 1983.
Russ Conway played a police officer. It's not clear in the film that Blanche is actually dead.
Crumbs - 2006 Whatever Happened to Baby Bodashka 1-2 was released on: USA: 19 January 2006
A child actress