Why does a mother insist on searching her daughter's phone and reading messages, despite the daughter expressing her discomfort, and is it likewise permissible for a husband to read his wife's conversations?

The mother or husband does not have the right to inspect the questioner's phone, read her messages, or view her private matters without her permission. This is because it constitutes forbidden spying, which is only permissible to prevent an evil when there is a clear suspicion.