Since she is represented by counsel, no other attorneys can really give advice on this situation. that attorney is much more familiar with the case. If you wish to hire another attorney to review everything in detail, you can do that. This seems as if the underlying case was extremely serious as it was 20 years ago.
Since your mother is represented she needs to communicate with her lawyer. As for a probation violation, that is very fact dependent. Mississippi is a state that does NOT appoint lawyers for probation violations.
If she does desire to seek new counsel be advised that this must be of a serious nature if this case is twenty years old and there is still a probation issue, unless this is a very old warrant