Anti-virus for Android is kind of....well, useless, because in order for one to get an infection you have to install an app, which means, the user will have to authorize the install and agree to the permissions, the antivirus will only tell you: Hey!, that's a virus!! and that's it, these infections will happen if someone installs apps from non-Google Play sites which is a risk and no amount of anti virus scanners will prevent getting infected because ultimately it's THE USER who allows that.
Regarding your question about what you should study, well, you just said it "Well I started to study malware in college." just pay attention in class.