The calculated distance (air line) between Nāḩīyat Saddat al Hindīyah and Najaf is approximately 48 miles respectively 77 kilometers.
By car or train, the actual journey to Najaf is certainly longer, as only the direct route (as the crow flies) between Nāḩīyat Saddat al Hindīyah and Najaf has been calculated here.
Air line (approximately)
77 kilometers
42 nautical miles