A. This really comes down to personal preference, the conditions you are sleeping in and any space or weight restrictions you have.
Pillows, even travel pillows, can be bulky to carry and take up precious space. Many hikers and campers will opt to take a pillowcase and fill it with their spare clothes. A fleece jacket, for example can make a great substitute pillow.
A travel pillow is a much smaller than a regular pillow, and often will attach to the outside of your rucksack. This can be a good alternative if spare clothing won’t do.
If your quality of sleep and mood in the morning relies on you having a pillow – then take one, your fellow campers will probably thank you for it.