What is this dinner for?

Min, Myung-hi, and Mum

Ok, now there is ME~* and Lena

Argh!!!! Bang Phoung ey kor a krok merl mess??? haha..

At first, mum said it's a goodbye dinner for Myung-Hi, our Korean Homestay Woman. But when there was Lena, my cousin who just pass her Bac II Exam, mum said, it's a celebration for her. However, when Bang Tourt joined, who got this graduation tmr morning, mum said, it's for his success. Ah... So in conclusion, what the party is for?