Tough situation...my experience with the summer after HS graduation has been "interesting".
I'm not sure it matters who calls. I doubt there is any scholarships available.
At this point, the DD should already have decided where she wants to go to school. It is kind of late to be changing course.
A lot depends upon how good your DD is.
The main goal should be to figure out what the college teams are doing. Most teams have tryouts in the spring. There will some kind of workouts in the fall as well as various team activities. There will be some fall "friendly" games.
All you can really find out is the schedule. It is up to your DD to participate in the fall and convince the college coach that she can play.
I've heard that there will be players that decide to leave or quit for whatever reason and won't return at many types and kinds of schools. Also heard a HC talk about cutting 2 girls for their next season. There will be plenty of schools that will still look at seniors in the summer. There are uncommitted Sr/Jr campus out there, if you look. Don't give up if she wants to play!
A lot of this also depends on what type of school she is targeting. I cannot speak for major D1, but I know that many D2 and D3 schools hold what they consider "open tryouts". The assumption is that most returning players will make the team, as will most preferred recruits. However, DD's team cut a few returning players in favor of incoming freshmen. Two of the incoming freshmen also made late decisions, but contacted the coach early in the summer and met her during the summer. That way when they showed up to tryouts, they had some knowledge of each other. Honestly, I'm not sure how someone would even find out about the "open tryouts" if they didn't have contact with the coach. DD received an email in the summer that was addressed to all returning players and recruits. She doesn't remember seeing any notices posted on campus. Without the email, she never would have known about the tryouts.
As others have stated, if she has already picked a school, I would suggest having her reach out to the coach as soon as possible.
Above is great advice. One other suggestion would be to look at the JC option. If your player has A+ (I'm assuming that translates outside of Missouri) scholarship is no longer in play. Playing at the JC level is a great way to get the experience and the looks from larger institutions down the line. It also allows your player to decide if playing ball while going to college is for her. It isn't for everyone. It can be very demanding.