1995 Ford Escort

My girlfriends car. She drove it from walnut creek to eureka, ca about 300 miles. Fine on the way. Ran through a large mud puddle in eureka. No problem yet. On the way, about 100 miles south on the freeway, the transmission just quit. No fluid loss. No noise, no warning. Just freewheeling. No fault indicator light. Gave it the smell test and didnt smell burnt any idea? Thanks ed