Does she "need" it - i.e is it a legal requirement - No its not.
If she was employing people then she would need to take Employers Liability cover and that comes along with Public Liability.
I agree that you can sometimes take these things to the extreme, but for the small premium this would be (and it will be small) in my opinion its worth it.
Happy to assist if you PM me some details.
This would be product liability, not public liability. AND YES she should have this.....Yes, of course. She will then be covered if a small piece of wire, a sharp edge on a clasp etc causes injury.