I wouldn't trust a door with a chain, if it fails shes dead.
Have her go to a window near the door and talk to people outside that way. Or have her answer the door with a knife at least 1' long and (edited, explicit content) stomach then (edited, explicit content).
I think a knife at least 1' or more would be your best option, you may want to go longer in case the intruder is overweight.
Last edited by AndersonG22; January 13, 2012 at 05:49 PM.