The calculated distance (air line) between Al Ḩudaydah and Ma'rib is approximately 165 miles respectively 265 kilometers.
By car or train, the actual journey to Ma'rib is certainly longer, as only the direct route (as the crow flies) between Al Ḩudaydah and Ma'rib has been calculated here.
Air line (approximately)
265 kilometers
143 nautical miles