The calculated distance (air line) between Mönchengladbach and Rüsselsheim is approximately 120 miles respectively 193 kilometers.
By car or train, the actual journey to Rüsselsheim is certainly longer, as only the direct route (as the crow flies) between Mönchengladbach and Rüsselsheim has been calculated here.
Air line (approximately)
193 kilometers
104 nautical miles