"Personal Antispyware" is classified as rogue antispyware. It installs itself onto the system and produces fake scan results to scare the unsuspecting into paying for it.
Malwarebytes' Anti-Malware has Personal Antivirus malware definition files. This means that this application should be able to remove the rogue antispyware from the infected system.
Download the file to the desktop. Once downloaded double click mbam-setup.exe and install it.
When the install is complete it will prompt you to update then run a scan. It is important that the program updates before the scan is run.
Perform the complete scan and remove everything it finds.
This should hopefully repair your dads computer.
Malwarebytes' Anti-Malware is good to keep on the system and run periodically.
If your dad is looking for free antivirus programs there are a few good ones (for personal home use) to choose from. If he already has one that he no longer wants or that has expired he must remove it first.
Be sure to only select one Antivirus program to install.