And she did download it after she bought this computer. she never own any mcafee CD's.
Run the removal tool for Mcafee. I assume that you have uninstalled it via control panel already?
I assume that you installed norton on your Mum's PC it is possible that it might need removal and reinstallation if the mcafee install messed up the install. If you are going to remove norton fopllow their recommended steps.
Moved this out of Community Help to General Discussion as a better spot.
As you say that you have Norton, its quite possible that Norton shuts down Windows firewall so that it can install its own Firewall product. However, you can check Windows Action Center if you are protected by a firewall or not.
It will look something like this.