Surname change for kids after divorce/split?

Dear All,

I have a question.
I have a female friend who has a kid with a guy. However, things did not turn out the way they wanted and they split (split for 4 to 5 years). In fact, they did not even register themselves under the marriage registration law of Malaysia (only went through a traditional wedding dinner with friends and relatives).
It was found that the guy had an affair somewhere else and that's the reason this couple split.
Through out this years, the guy did not held any responsibility for the kid and he only paid like RM200- 300 once in a blue moon (whenever he feels like paying).
In the event where the mother wants to change the surname of the kid following her mother's surname, where should she go to? and does this change of surname procedure needs the concent of the irresponsible father?? (non registered couple)
Can anyone out there please help and advise?

Thank You
Regards,
Nick