The calculated distance (air line) between An Muileann gCearr and Malahide is approximately 49 miles respectively 79 kilometers.
By car or train, the actual journey to Malahide is certainly longer, as only the direct route (as the crow flies) between An Muileann gCearr and Malahide has been calculated here.
Air line (approximately)
79 kilometers
43 nautical miles