I use kaspersky internet security, and also have free versions of malwarebytes and emsisoft emergency kit as back up scanners, emsisoft also use bitdefender database.
A complete free package would be avast coupled with comodo firewall give excellent protection, however comodo doesnt play nice with windows sometimes causing headaches.
Another free package making the news is 360 total security, which also uses avira and bitdefender engines, however you must turn these protections on. It also has a firewall which seems more than adequate just behind top suites. Most people cannot fault this package other than the fact that it is a Chinese product.
On my personal PC at home which i've had since 2012 (upgraded few times hardware and software) I've only run MSE (which is not an anti-virus program), and I never had any viruses. Once a month I run malwarebytes, and never found a virus or a trojan.
Same is true for my prior computers.
At work we use Trend-micro which IMO is as useless as Norton, and I may replace with Kaspersky (had good experience with this one at other offices).
Well, thank you all for your answers.
I've decided that I'll just have my mother buy Bitdefender.
(She's not that great with computers, and tends to think that not buying an antivirus is dangerous, there's not convincing her otherwise. So,I'll save her some cash and have her get Bitdefender for cheap.)