It seems your friend may have sent you the picture for a few reasons. One possibility is that she wanted to share a moment with you and include you in her life, even though you live in different states. Taking a picture together and sending it to you could be her way of staying connected and letting you know she was thinking of you.
Another potential reason is that she may have been excited or proud to be spending time with her friend, and wanted to show you the two of them together. Some people enjoy documenting their social activities and sharing them with friends and loved ones. She may have simply wanted to update you on what she was up to and who she was with.
Without more context, it's difficult to know for sure why she chose to send you that particular photo. But the act of sharing a picture of herself and her friend suggests she may have been trying to include you in her day, or simply wanted you to see who she was spending time with. The motivations behind such actions can vary from person to person.