Try to not sit next to H on the bus, and that should fix the problem.
It could very easily be that P is testing you, but it could also be that H also has a crush on you, and if you let H act this way, it will give you problems regardless of which one it is.
The easiest solution is to simply not sit next to her.
If that doesn't work, tell her the situation, and ask her to keep her hands to herself.