Easiest way is to drag the composite video to a thumb drive and then transfer the thumb drive to your family members. You may need to make several thumb drives according to the number of people to whom you will be sending it. If the thumb drive will be played on both Apple and Windows devices, then you should format the thumb drive in the ExFat format. If only to be played on Apple devices, then you can format the drive Mac OS Extended (Journaled).
Burning to a disc would work as well, if you have a DVD burner and some standard DVD discs. If your movie is less than the 4.67 GB size of a standard DVD, you can use the burn program on your Mac to burn a data DVD (see Finder Help menu instructions). However, data DVDs likely will only play on a computer and not in a standard DVD player. Movies larger than 4.67 GB in size would need to be burned with DVD authoring software that can compress a larger movie to fit on a standard DVD. Authored discs will play on both a computer or standard DVD player. Apple's authoring program, iDVD, has been discontinued. Others on this forum have recommended DVD Creator by peng GUIPING as a replacement. I believe that you can purchase it for about $14.97 from the online App store.
-- Rich