The timing of the violation relative to the end of probation matters here, and the picture is actually more manageable than it might feel right now.
When someone violates probation, the standard outcome is revocation and serving the remainder of the original suspended sentence. That is the worst case. But the remainder of the sentence is the key phrase. If his probation runs through March 2019 and he did not pick up a new criminal charge, the remaining time left on his original sentence may be relatively short at this point.
Probation violations without new charges are treated differently from violations that come with new criminal conduct. A judge looking at someone who violated a technical condition near the end of their supervision with no new offense has more reason to consider options short of full revocation than one dealing with a new crime on top of the violation. The conversation at that hearing is about what went wrong and whether the person can complete the remainder of their obligation without further incident.
If the probation was genuinely close to ending and the violation did not involve new criminal behavior, a judge may impose a short custodial sanction, reinstate probation with stricter conditions, or allow the remaining months to be served and close the case in March as originally scheduled. None of those are guaranteed, but they are realistic outcomes depending on the judge and the circumstances.
The most useful thing that can happen between now and the hearing is getting an attorney involved who knows the local court and can make the strongest possible argument for why revocation to the full remainder of the original sentence is not warranted given the timeline and the nature of the violation.