My daughter was praying salaat layl and she says she heard a whisper near her ear while she was making dua and is confused what that was and is scared now to pray alone. What could that be?

She should ignore this and do istiadha from Shaitan. It could be internal thoughts. Prayer is powerful and nothing should stop us from doing it alone. She should give sadaqa and ask Allah for strength and protection and she will be ok Insha’Allah