You cannot train, for night time dryness.
She is so young.
Daytime pottying and night time "dryness" are 2 different entirely separate, things and processes.
Night time Dryness... is not something that occurs, until even 7 years old. It is not the child's fault. It is all about PHYSIOLOGICAL development... of the brain/myelin nerve sheath/bladder development.
This is normal.
Using pull-ups for night time is useless. Because, it does not hold much and it leaks. Just use night time, diapers. Huggies.
My daughter was already 7 and still had night time accidents.
My son is 5 and still wet at night and wears night time diapers for sleep/naps.
Normal.
ALL of my daughter's Teachers... from Preschool and Kindergarten and 1st Grade... ALL unanimously said: that kids these ages, still have night time accidents/are still wet/ and use night time diapers. It is, normal. But the parents are embarrassed about it. But it is normal biological development of children these ages.