The calculated distance (air line) between Carrickmacross and Droichead Nua is approximately 55 miles respectively 88 kilometers.
By car or train, the actual journey to Droichead Nua is certainly longer, as only the direct route (as the crow flies) between Carrickmacross and Droichead Nua has been calculated here.
Air line (approximately)
88 kilometers
48 nautical miles