Why was dorys mum crying?

Why was dorys mum crying? When she believes the truck is taking her daughter away forever, she begins to cry until she watches her daughter come back. By the end, she trusts her daughter and tries to remain close to her, telling her to come home later for a family swim.

When she believes the truck is taking her daughter away forever, she begins to cry until she watches her daughter come back. By the end, she trusts her daughter and tries to remain close to her, telling her to come home later for a family swim.