How to merge 4 Audio and 1 Video .MXF files in to one h.264 video file on Linux using ffmpeg?
I used ffmpeg with only '-i' switch to figure out which stream was audio and which was video. Then executed the following to merge two audio channels and its video. 

ffmpeg -i 0007WA.MXF -i 0007WA00.MXF -i 0007WA01.MXF -filter_complex "[1:0] [2:0] amerge" -c:v libx264 -c:a aac -strict experimental -qscale 0 -y  ../ffmpeg-att2.mp4


I think there can be more options by utilizing all four audio files to make stereo or surround. However, I stopped here as the output was acceptable. Note - used '-qscale 0'  to limit quality-loss.