As a response for where she is, are all the following grammatically correct?
"She's out at a party with her friends."
and
"She's out with her friends at a party."
Do both the above responses mean the same? Are both of them grammatically correct? What other way could one respond to mean the same?
Both of them look pretty all right to me. You can add punctuation to the second sentence, which is my suggestion.
"She's out, with her friends, at a party."
Also a simple alternative to this sentence would be :
"She's out partying with her friends."
The only problem with this sentence is that, it doesn't specify whose party it is. When you say "...at a party", it usually means that the party is hosted by a third person and the subject is attending it. Here, the party can mean a party organised by an unspecified third person or even a simple get together organised by the subject with her friends. So it is an optional alternative, but it can mean a different thing too.
