Finding someone to help you at a moment's notice is one of the most difficult aspects of aging, especially if you don't live near your family.
I'm fortunate because some of the ladies in my Active Adult Community have started a community outreach program called Have a Heart. They have several groups that will help out with everything from delivering homemade meals to driving you to the doctor.
If you can't find a group in your subdivision or church to help you out, then just go to the Internet and type in: Senior Outreach + your city,state (like Senior Outreach + Denver, CO)
That should give you a listing of several organizations in your area.