Xavier (24-3) won for the 10th time in 11 games and matched its highest victory total since the 1983-84 season. Five days after surrendering a season-worst 91 points at Tougaloo, Xavier allowed less than 60 points for the 12th time this season.
Simmons scored his most points since Dec. 29, and Miller tied his career high. Both are sophomores.
Miller’s 3-point play with 19:37 remaining put the Gold Rush ahead to stay, 30-27. Xavier took its biggest lead, 58-45, after Chris Iles’ two free throws at 6:02.
Iles scored 10 points and made 8-of-8 free throws for Xavier, which made 21-of-27 from the line and outshot Mobile 47.7 to 39.1 percent from the floor.
Donte Walker scored 17 points and Ji Kimbrough 13 for Mobile (13-12).
The teams were tied at 27 at halftime after nine lead changes.
Xavier swept the two-game season series and leads 28-25 all-time after beating the Rams for the sixth time in seven attempts.
The other times Xavier won 24 games since 1983-84 were in 1992-93, 2000-01, 2004-05 and 2007-08.
The Gold Rush will play Gulf Coast Athletic Conference opponent SUNO at 7 p.m. Saturday at The Barn. After playing four straight on the road, Xavier will close the regular season with two GCAC home games.