Can I install two antivirus on the same computer

Can I install bitdefender free edition v10 and avast 4.8 edition on my same family pc?

This is not recommended, there may be conflict so you have to disable one of them.

I use Avg free version. Apart from Avast & Bitdefender you can also go with various anitivirus softwares: http://forums.techarena.in/guides-tutorials/1014226.htm

And for antivirus removal tips see this: http://forums.techarena.in/guides-tutorials/1016800.htm