I need to show a double arrow at the beginning and end of a road feature. When I use arrow in QGIS 2.18 every intersect has separate arrow like this:
The issue you see is caused by the fact that the arrow symbol layer renders curved arrows based on only three points. The roads in your example clearly consist of lines with more than three points/nodes.
In such cases, arrow symbol layers are not useful. Instead, follow the instructions in Showing arrowheads in line end using QGIS?