Where does he get the names from at the moment?

Getting the subscribers from the API automatically involves quite a bit of setting up.

If there's an easier way that than to get them into a text file, then you can simply loop over every line of the text file and add their points.

Here are three posts about using subscribers:
https://forums.mirc.com/ubbthreads.php/topics/245691/Twitch_Subscriber-only_command
https://forums.mirc.com/ubbthreads.php/topics/244141/Welcoming_a_new_Subscriber
https://forums.mirc.com/ubbthreads.php/topics/244032/Twitch_Bot_Check_Subscription_

I would not use twithclient or twitchnotify to obtain your list because these do not provide a mechanism for removing users who are no longer subscribed.

To make sure this does not happen more than once per month I would suggest storing and comparing the last month and year the command was run.