The calculated distance (air line) between Humen and Yuen Long Kau Hui is approximately 34 miles respectively 55 kilometers.
By car or train, the actual journey to Yuen Long Kau Hui is certainly longer, as only the direct route (as the crow flies) between Humen and Yuen Long Kau Hui has been calculated here.
Air line (approximately)
55 kilometers
30 nautical miles