Is it permissible to hit a daughter who is negligent in prayer and 18 years old, after repeated attempts at admonition?

The mother must continue to advise her daughter and guide her towards prayer. She can use means such as depriving her of her affection and cutting off financial aid if necessary, or even striking her if that proves effective. However, the best approach is counsel, encouragement, and deterrence, by explaining the reward for maintaining prayer and the punishment for abandoning it.