AWS EC2 access from only selected systems

I am running a AWS ec2 server running windows server 2016. I have multiple users logging into the server from multiple office locations all over the country, currently with just the IP address and the password anyone can login from anywhere in the world and access my data , I am looking a solution where I can block the access from an unauthorized system or have another layer of security with which we can block unwanted access and allow access from only selected computers and or locations.