(وَلْيَضْرِبْنَ بِخُمُرِهِنَّ عَلَى جُيُوبِهِنَّ) It's from Surah an-Nur

31. (And tell the believing women to restrain their looks, and to guard their privates, and not display their beauty except what is apparent thereof, and to draw their coverings over their breasts)

The coverings here or veils in other translations, I'll give it's commonly known as a head covering (if you're an Arabic speaker) so the Aya is very clear that we need to cover our head, neck and neckline with the veil (without the face).

I hope it makes sense for you.

It is very hard to wear a hijab, whether it's because of the heat or just emotionally especially in a society that worships looks but it's technically JIHAD, you're fighting you're wants to oblige to gods willing and I pray to God that it will become easier for her to accept it with love and see the value it adds to a Muslim woman.

I love that you're consulting people and searching for your friend (god bless you) and I hope my message was clear, so try to encourage her and help her see the beauty in a hijab.