Children's church or Sunday school.
An overnight church service is called a vigil.
The narrator's mother was waiting for the children after the church service.
The people attending a church service are called a congregation.
Aunt Alexandra
The sanctuary is where the main church service is held
The hymn recited after a church service or mass is called a recessional hymn or a benediction.
Calpurnia, their housekeeper/nanny, dresses them to go to her own church.
The final service of the day is known as Compline.
It is called a few names. Sabbath service, service, weekend service etc. Chapel or Church are more colloquial names.
The people attending a service are called the congregation, although sometimes they are called churchgoers.
When a priest speaks in Church as part of a Liturgy or Service, it is called a Sermon.
Peppermint sticks or canes were given to children during church services to keep them quiet on Christmas. The treat served as a distraction and incentive for children to remain quiet and well-behaved during the service.