If you have changed the IP of your PC and you forgot to kill previous instance of mongo. Then, you will get an error with code '100'. If you change the IP in mongo.conf file then still you will get error. So to resolve this problem you have to first kill the previous instance. Then set the config file for mongod. Below is the code which resolve my problem.
ERROR: 'mongod.service: control process exited, code=exited status=100'
kill -9 $(pgrep mongo) sudo mongod --config /etc/mongod.conf mongo --host 192.168.2.2