AntiVirus software for a 2012R2 VM fileserver

We have a new Windows 2012R2 VM running on Hyper-v. This is going to be a file server and we will transfer a good amount of files from linix server.  It will hold 10Tb of data and will have shares for users on the network. Should we put an antivirus software. We have licenses for Symantec endpoint , but I was thinking of putting something on from Microsoft. I was told there is something free form Microsoft . What do you think about Symantec and also what Microsoft options are there for someone that will not have System Center. We just don't want to pay for system center licenses, but would be welling to just pay for stand alone anti virus software.