After some discussion about the pros and cons of inventing a way to depict the arrows as braille symbols, the consensus is to use tactile graphics to represent the arrows which are printed above the number line. If the upper (blue) arrowhead is above blank space, a light lead line should be added, leading vertically down to the number line from the arrowhead.
When this method is first shown in the book, explain in a transcriber's note that the lower arrow (gold in print) is read first, then the upper arrow (blue in print) unless the narrative is clear enough.
If this is for grade level 4 or above, the number line and its labels may be done with braille symbols as outlined in Unit 6 of Guidelines and Standards for Tactile Graphics. See section 6.5.1. Note that you may shorten the length of the number line in order to fit it on the same line as the answer choice identifier, to the right of each subitem.
If you have further questions regarding the tactile graphic, please post your question on the Tactile Graphics forum.
Thank you for your question.