Some antimalwares may detect some viruses but not most of them and the same applies to any antivirus... they may detect some malwares but not most of them. So, you may need a specific type of security program for each type of infection. And besides, free versions of antimalwares only offer scanning detections, with real time protection requiring payment. Some free antivirus programs may offer online protection and some may not... all paid versions offer online protecion.
For malware you need an antimalware... Malwarebytes Anti-Malware is the best.
For viruses you need an anivirus... Avast is the best rated antivirus with online protection.
For Adware (in case of) you'll need AdwCleaner
For stubborn virus infections, an Avast boot...