Linux has been mentioned - several times then was moderated as troll or off topic. Since it a college student, they will most likely need windows - depending on the classes so linux may not be an option.
I use mse and malwarebytes for all my security needs on my windows computers. In addition I use housecall for a second opinion. The biggie about mse is once you install, you can forget it. As you go about searching for a free antivirus, be sure to check their features. I have used most of them at one time or another. Watch out for the following issues.
1. only allowed to install on one computer in a household
2. popups wanting to sell the paid version
3. ads in general
4. have to manually update or scan
5. heavy resource usage - especially on older computers
That said, when paying bills online or doing anything that could lead me into areas that could bring about malware, I will boot to linux.