回複：Thank you so much. His son will be graduating

Are you saying he can stay until then under his current H4 status?
-No. I mean he can change his status to F1 if he will graduate from a public high school within 12 months. Immigration law only allows an international student (F1 status) to study in a public high school for maxium 12 months, but no such limitation in a private school.

When the H1 status is invalid, H4 status is also invalid. So, the kid needs to change his status to F1 for lawful presence.