FortiClient is not the most robust AV / Anti-Malware solution available, but it is free and full featured, meaning it is a good option for endpoints with no protection.  Fortinet provides both Windows and Mac versions, providing plenty of client flexibility.

http://blog.fortinet.com/2017/02/24/forticlient-scores-high-in-the-latest-advanced-endpoint-protection-report-from-nss-labs