I need help killing a khezu. I hate this thing a lot. It is a 3* guild..

Take a fire weapon such as rathalos fire sword or blazing falchion along with you, because Khezu are weak against fire. You can use pitfall traps to get extra hits on it. You need to take hot drinks with you, because in the caves your stamina goas down quickly, meaning it is difficult to dodge the khezu's attacks.
I find that when it does the body shock it is easier to block it, than try to roll out of the way.
If you hit it in the leg, then it trips easily.
If you want to get it off the roof, then stand exactly underneath it's shadow. It won't drop onto you though. It will try to, but it will land a little bit in front of you, so as long as you are standing exactly in the middle of it's shadow then it won't hit you.
Always let it make the first move before attacking it, because getting caught out by it's body shock can be costly. Eg. It will turn towards you, run to the side of it, but don't attack it, stay just out of distance. Then if it doesn't body shock, attack it in the leg.

You can use dung bomb (dung + bomb material) because the khezu works by smell, but I have no idea what it does...

Get a good weapon like use the garuga cheat and make one of the raven weapons the sharpness is in the blue zone and has 250-900 attack.