The calculated distance (air line) between Maulavi Bāzār and Āmbāsa is approximately 39 miles respectively 62 kilometers.
By car or train, the actual journey to Āmbāsa is certainly longer, as only the direct route (as the crow flies) between Maulavi Bāzār and Āmbāsa has been calculated here.
Air line (approximately)
62 kilometers
33 nautical miles