I'm not fond of any sprays, in my opinion the only way to effectively "blind" an opponent is with actual material. Sand, glass, ash, salt, that stuff. But, I believe that's kind of illegal in most cases.
Stun Guns, Taser is a name brand, are a decent choice. They make a noise that incites fear. The main reason, I think, the police don't use the contact guns is because you have to keep that contact. A gun that shoots electrodes should be better, but training may be an issue. Although, I don't know her or the options available to her. I'd stick with a model that has seen good use and is easy for carry.
In any case, be sure she is willing to carry it properly so it may be accessed, use it on a threat without hesitation, and most importantly be sure she can use it effectively. Practice is always the key.
Normally I'd suggest a knife, but she's not likely to want to use it, ever. I just believe it's far better in any situation where she is on the ground. If it seems she is okay with it, I'd check out IET: Inverted Edge Tactics. Again, practice is the most important factor.
"Today is victory over yourself of yesterday; tomorrow is your victory over lesser men." - Miyamoto Musashi
[Insert random irrelevant religious quote here]