Answer: a wedding
Never having been married herself, Donna had mixed emotions as she prepared for the wedding of her 20 year old daughter, Sophie. She had raised Sophie by herself, and while she wanted her to be happy, she felt that she was too young to be making such a commitment, and worried that she was doing it for the wrong reasons. She had her hands full with the regular wedding preparations, while welcoming her guests into the rather rustic hotel she ran, that was in need of serious repairs.
Donna was played by Meryl Streep and Sophie was played by Amanda Seyfried.