The guide to install MongoDB Node.js driver on earlier versions need to specify version number:

http://mongodb.github.io/node-mongodb-native/2.2/installation-guide/installation-guide/#mongodb-driver

npm install mongodb --save

Should be something as below:

npm install mongodb@2.2 --save

Without version number specified, the command will download the latest package version v3.+ which is not backward compatible to v2.
i.e. if someone would follow the installation/tutorial guide they would encounter issues