Well, if she's desperate enough to do something really stupid, she could grab ammonia and bleach from under the sink and douse the guy. You'll end up creating Hydrochloric acid on the surface of his skin (highly corrosive), but it will also make a highly toxic gas, so she'd have to get out of the room really fast and hold her breath.
Another consideration is that anything aerosol - cooking spray included - can be used to make a fire sprayer if she holds a lighter in the stream. Just make sure she lets go of the lighter before she lets go of the sprayer.
If you're going old school, then consider the toxicity of silver to vampires. Heirloom dinnerware, maybe granny's silver serving set, will have pure silver knives in them.
That is semicorrect. The stake has a both literal and symbolic function. Since vampires are magic, the symbolic is just as important, as magic is all about symbolism.
The preferred method of actually killing the vampire is decapitation. apparently both are necessary. Perhaps the body could retrieve the head if not nailed down. I've never read that, but it seems to follow.
It's not actually. Vampires as "magic" isn't part of the older lore at all. Vampires were bodies without spirits (which is why they cast no reflection). In other cultures, they're other things/
The decapitation part came along somewhere around the dark ages, as did the idea of the stake (read up on Dom. Augustin Calmet and his treatises involving the story of a supposed vampire who thanked him for the stake in the heart as it gave him something to beat the dogs off his grave with). In those instances, even decap. wasn't enough - you had to fill the mouth and neck with garlic and bury the body in a lead-lined coffin.