This is the moment MeBai and her mother Mae Yui are reunited after a separation of over three years. MeBai had been sold to a trekking business in Thailand when she was aged 3½, but was too young and began to lose weight, so could no longer work.
She was then taken to the Elephant Nature Park.
Her mother Mae Yui, worked for a different trekking business. Lek Chailert from the Elephant Nature Park discovered this and contacted Mae Yui's owner who agreed to retire her so that she and her daughter could be reunited and live free together at the park.
There's more information about the story behind the reunion here and here.