A "bump" is much gentler than a "hit". If someone falls to the ground, it would generally be described as a "hit" not a bump". For example, "she hit the ground when she fell from the step" or "he fell and hit the ground when he stumbled". It is very normal for people to use the expression, "hit the BACK of her head". if they want to be specific. If the details are different, people say things like, "she fell and hit her nose' or "she fell and broke her teeth". Hope this helps

They're all good, though the first can be misread; in your other sentences what she fell on was the floor; obviously her head can't play the role of the floor in this story, but the act of thinking this through wastes brain time and make the text slightly harder to read. If you want to say it unambiguously, but without mentioning the floor, you could simply say "she fell and hit her head", which is how I think most people would say it.

I personally would say wooden floor but you're right

I think these three are correct