I concur with equipping her with OC and perhaps lawful concealed carry. Buy extra OC and PRACTICE with it. In my opinion, she must also receive professional self defense training using pistol if she chooses this route. (Just buying her a handgun that she tosses into her purse is not enough.)
I'd also read and have her read
The Gift of Fear by Gavin de Becker, which discusses stalkers and pre-incident indicators.
http://en.wikipedia.org/wiki/The_Gift_of_Fear