K.O.
If she is potty trained during the day and not have excessive accidents throughout the day, then she can definatley be potty trained at night. My son was 2.5 and fully potty trained day and night. He is 3.5 now and every once in a while we have a nighttime accident, I bought a padded liner to put under his sheets to protect the mattress if he has an accident.
I cut liquids out about 1 hour sometimes longer before bedtime and make sure that he goes potty right before he goes to sleep. And he does just fine.
Good Luck!