Staying home alone overnight. What age?

Just curious what people think is a good age for teenagers to stay home alone, overnight?

My brother & SIL's first bub is due now and we'd like to go see them when bub arrives. The issue is that they live 3 hrs away from us. Our 16 yr old DD works part time and is more than likely going to be unable to come with us at such short notice but she suggested that perhaps she stay here at home by herself.
She's very mature for her age, reliable and I know she isn't the type to throw a party or get into mischief. She has 3 friends that she works with who live the next street over from us, so I know that if she was concerned, she could go to one of their homes.

I'm just torn. Part of me knows she could do it and would love the freedom & responsibility and yet the other part of me is worried she may be too young.

Thoughts?

Instead of staying home alone could she maybe stay with one of her friends (I only say this because I dont like staying home alone and Im 30 something).

But if you are comfortable leaving her home alone I think 16 is old enough and as you said she is mature for her age.

If she's a mature girl and you trust her then I think at her age it should be fine

I moved out of home when I was 16.
Unless she is very immature IMO she is old enough to spend a night alone with clear guidelines about what she can and can't do.
Maybe she could have a couple of friends over for a girl's night in - movies and pizza.

I was living independently at 17 (almost 18) so I think 16 is fine. At that age I would have been left overnight with two siblings to mind.

My DH moved out at 15 (and he's not even that mature lol!). I was having nights alone and looking after my brother (22 months younger than me) from around 15, my mum worked two jobs through most of my teen years to put us through secondary school. I like Zazou's idea of a girls night in :)

I used to babysit my 9 year old brother overnight while mum was at work when I was 14. I would expect a 16 year old would be well and truly old enough to stay at home alone.

I was staying overnight at home at that age and I'd have no problem with my 16yo staying home alone overnight either.

What's her plan if she starts to get scared? Can a friend also stay?

I wasn't staying home alone til 18! But we lived on property and I was too scared!!!
16 is old enough if she feels comfy and has someone to call if she gets worried.

I would say she is old enough, but I agree with other suggestions of having plans in place if she gets scared. I used to always hear noises and get scared when home alone. Even now I'm not a massive fan of it.

Thanks everyone.
The issue with her staying with friends is getting too & from work. The bus that takes her directly to work is directly opposite our house. She can't stay with one of the friends in the next street and she can't stay here as she is from a strict family who don't allow sleepovers of any kind. She could certainly call on any of the girls to have a pizza night but they wouldn't be allowed to stay - especially without parents here.
If she got too worried, my good friend would pick her up at absolutely anytime and let her stay at her house.
I feel like she'd be fine. Thanks for your suggestions and advice everyone :)