My child likes Minecraft. Are there ways that I can teach him Linux and Minecraft at the same time? I know there is an outdated version of Minecraft that runs on a Raspberry Pi and purportedly has some sort of programming lesson that could go with it.
There is a clone of Minecraft called Minetest that runs on Linux. It has a lot of configurations that can be made using Linux tools, like skins, world definitions and games built inside of Minestest.
which one of this can be taught to a 9 year old and how Linux is the best option because there are a variety of distributions available for it, so it is the most versatile and can be tailored to the needs of you and your child. 

The best way to teach children how to use Linux is to give them an incentive to use it, and they will be motivated to figure it out on their own. One of the things you could do is install games. You could also have them work on a Raspberry Pi project together with you to help them to learn how to use it. There are a plenty of fun projects online that you could work on.