Questions:
Are you a Mac user yourself?
Or a PC user?
Do you know what application your father used to manage/view the photos?
Was it iPhoto, by any chance?
If it was iPhoto, you must realize that the iPhoto library is kind of an "incomprehensible jumble" of scattered images when viewed with anything other than iPhoto (or Apple's new app called "Photos").
If one is going to "export" that entire library for use with an app OTHER THAN Photos, probably the best way to do it would be either to use iPhoto (running on the Mini) to export the entire library (I'm not even sure if that's possible, I was never much of an iPhoto user), or, use a 3rd-party utility designed to do something like that.
I think there used to be an app named something like "iPhoto Library Manager" or similar.
You'll have to look around for that or similar apps.
The goal here is to get the pics all exported in a folder/file hierarchy that is understandable and navigable, that can be used elsewhere.
Final thoughts:
If you want to just get the pics off the Mini onto a cross-platform drive to be read in Windows, use a USB drive. You DO NOT want "ntfs" -- use something else, like exfat.
If the files are going to be used on another Mac, use HFS+.
In Apple's Disk Utility app, that's called "Mac OS extended with journaling enabled, GUID partition format".