Good old Frankie. Well done

A: Oh, why should I never play with matches? Oh.
B: Because matches can set things on fire, the way you set the wastebasket on fire.
A: Yes, but after I set the wastebasket on fire, you put it out.
B: Now, luckily it was only a small fire and I put it out in time.
A: Yes, you did put it out on time. Good old Frankie. Well done.
Oh, what's this thing you put the fire out with?
B: That's the fire extinguisher; to extinguish fire; to put fires out.

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1- Which is grammatically correct:

A- Good old Frankie. Well done ? original text

B- Good old Frankie, Well done ? comma

C- Good old Frankie; Well done ? semicolon

2- What does "Good old Frankie" mean?

Does it mean "Dear Frankie"?

Thank you