You need only one Firewall and one antivirus. you should have only one real time scanner for malware. However you can have as many of the on demand scanners that you want.
I do not recommend Spybot S+D anymore as it only update once a week. The way that new malware are coming out each minute.
On my own PC I use the Fallowing:
Antivirus: Avira Antivir Personal (Free ed.)
Firewall: Comodo Firewall (Free)
Note: It is part of the Comodo Internet security suite. However you are able to chose the parts you want to have.
Antimalware: Malwarebytes, Windows defender, Supperantispyware.
Others I found useful: Spywareblaster, a host file, and Web-of-trust (WOT) for my web browsers. I also use Sandboxie to run my main web browser in a 'sand box'. Also with Firefox I use NO-Script. I am using C-Cleaner to clean out all of my temp files and recycling bin out.
Make sure that you have windows update set for automatic.
What you use is up to you. Also do a mix and match to see what will work well together. Remember that you are your worst security treat. No security program can protect your PC from your self.
There are a bunch of recommendations and CNET has a security software "starter pack." However some of the things recommended are redundant. I just switched from AVG free to Avast free but what do I really need in addition? Do I need Spybot? Malwarebytes? I did add Last Pass but then saw the other program that does the same function (can't remember the name.) In a nutshell, what are the recommendations for what I need to cover myself all the way around?
Thanks for opinions...