I'm in 2 minds about the spray. On one hand it empowers them but on the other hand by buying into it you're saying (in not so many words) that 'yes, there is a lion, monster etc' which can make it more real and scary.
Maybe you can get her a torch and tell her that having a torch helps you to be more brave. That way you're not confirming that there is a lion but still giving her a means of empowerment. She can also use to torch to check for lions so she can see that there isn't one. You could choose an essential oil that is calming and soothing to help keep bad dreams away.
Have you spoken about it durin the daylight. If you talk about it now it might help. I liken them to TV they might be scary but they're not real and they can't hurt you.
It's kind of a hard line to tread - to show empathy for their fear and recognise that the fear is real whilst not buying into it too far.