I was going to reply to a previous thread about antivirus for Windows 95 and Windows 98, but the thread locked after 6 months. So hopefully someone that still needs more up to date info will find this thread useful.
Avast Antivirus has been an excellent product for me on the DOS-based Windows 9x operating systems as well as newer releases such as NT 4.0, 2000 and XP. The company celebrates its 25th anniversary this year.
Avast version 4.8.1368 still supports Windows 95 and later operating systems. It is the only antivirus I know of that releases updates for an OS that will be celebrating its 20th anniversary next year. It is a great program and only requires Windows 95 with a 486 processor and 32MB RAM.
Support for version 4.x was supposed to end years ago, but I actually took a screenshot of it updating as recently as March 2014. The daily database updates are available in standalone format on their web page. http://www.avast.com/en-us/download-update
You can get still get version 4.x from Filehippo or from my FTP