بسم الله الرحمن الرحيم
It is correct to name a girl Naila. It is an Arabic word. It means donation, generous, achiever. It has also been the name of some sahabiyat. It is also the name of the wife of Hadhrat Usman Ghani (رضي الله عنه). You may keep this name, but the suffix of Muntaha does not seem suitable.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.