OP,
Your friend sounds nice BUT she has brought an ignorant twat to your home.
Not cool.
Your first trip away with someone should not be such a huge imposition of 5 nights in the home of a good friend IMO.
Your good friend should know better and appreciate your huge hospitality enough not to bring a disrespectful rude pig to your home!
I think you need to make that point to her.
Her friend is the type of entitled twat that thinks that being put up is nothing.
Fxxk that!
Years ago I shared an apartment and my flatmate had a friend and her boyfriend to visit and stay.
She came back a bit earlier with her friend on the first night and he stayed on in the local bar.
He came home late, left the front door wide open, clearly pissed.
I found the door open and told my flatmate, neither of us were impressed.
She mentioned it politely enough and he actually said "chill out" to her.
My flatmate did chill out, right after she told him to "get his shit together and get out of my flat".
Her friend was mortified and left with him.
They apparently had a huge row and she abandoned him and turned up at ours later.
When you are bringing someone to the house of another person, you are responsible for their behaviour.
Your friend needs to realise that.
I think she should be telling her to buck up and apologise, or leave.
Either way I wouldn't put up with such hugely generous hospitality being abused by them.
I would learn from this re what type of friends of friends come.