At this age, legally and emotionally, autonomy is important in these situations. Parents can lead the horse to water…but… I think it is important to welcome a kid home, offer help and support, but most of all offer confidence in the future. Parents and young adult can discuss problems and solutions but unless depression is severe or there is danger to self or others, the kid needs to lead the way, which is tough (sometimes especially with boys!).
Transition to college is tough for everyone. And far away from home, sometimes more so. It is like falling off a cliff when it should be a gentle slope. This could be an adjustment issue. It is also the age when some mental health issues arise. It is impossible to know on the forum and I wish the family the best in dealing with the uncertainty.
Many of us have gone through this and over time, seen things work out really well.