I've had to travel to see my family and friends for over 7 years and I can never spend enough time to see everyone I want. When I have a short trip, I prioritise who I see, those who I keep in good regular contact with and then the rest, well they just have to wait. When I have a longer trip, I try hard to meet with everyone ,though it does become quantity over quality sometimes
Like Bmore, I end up doing a shedload of driving as well.
Lucky for me though, I have really cool parents that everyone actually likes to hang out with, so I have friends who will come down and hang out with all of us.
I like the idea of a pub night so people can come see you, or a meal out, or something social where you can see lots at once. Interestingly enough, you know who your true friends are if they're willing to make an effort to come see you at a local pub-party-parent's house- rather than the other way around. Of course, there are exceptions to the rule (as you can't meet everyone's schedules) but still gives you a good idea
Don't feel guilty about seeing your friends and not spending every waking minute with your mom. Its your holiday, your time, your life. Try and find a balance. It is hard though, I don't envy you having only a week either.