How do i get a colonoscopy done if i dont have anyone to take with me?

Pearl, supposing the remote possibility you live within range of the map co-ordinates 
Latitude: 44°31′00″ N 
Longitude: 80°00′58″ W
I could make myself available to accompany you to wherever the place of appointment.
I am more or less free anytime.
Let me know if I am close enough to your location.
Tony

Well sometimes places like the Salvation Army have a free ride service to get people to doctor appointments. and also give you a ride home. Cheers and happy weekend! 

its not about the ride, i can get a medicaid cab for free, they just cant sign me out and they wont do the colonoscopy if i show up by myself, i dont even drive so they shouldnt have to worry about me driving there and back

I'm guessing it's because they sedate you, correct? If so, then it's because they want someone to stay with you until the medication is out of your system to make sure you stay safe and don't have any odd reactions. At least that's how it was in dentistry. Some places actually require the driver to sign something saying they'd say with the patient for the rest of the day, while others just talk to the driver/ caregiver and give them instructions too. Either way, that person is assuming some responsibility for you, so most transit companies can't be your person.

Craigslist scares me because, if you are sedated, you will be vulnerable after the procedure. It's not good to have a stranger with you. They may just bail and leave you or they may rob you blind... or worse. 

Talk to the office and ask them what they recommend. Surely they've dealt with this before. If they're unhelpful, find out if having it done in a hospital is a possibility or talk to your casewoker (or anyone at the state medical agency) to find out if you qualify for some kind of extra assistance. Perhaps you may qualify for specialty medical transport or for a caregiver for the day. Odds are, you will have to jump through some hoops to get it, but given your history, the test is 100% medically necessary, and so there are likely options in place from the insurance company that oversees your plan or the state itself to handle these sorts of issues.

Failing that, check with your church or other community organizations in your area. 

Because this is specific to your location, you will need to ask at the clinic what service they recommend. I volunteer in an outpatient surgery waiting room and I can tell you that there are many patients who do not have friends or family to accompany them. They use non-emergency medical transport companies. In my personal experience, I used a medical transport company to go to the doctor when I had two broken arms. It wasn't like a cab ride, they came inside to get me, took me into the waiting room and then returned when they were called to pick me up. There may also be some options for low-income patients if that applies to you.

If you have Medicaid they pay for medical transport.  The driver should go in with you to assure the facility that he will, when called by the facility,  personally pick you up and drive you home.  I saw this when I had this same test some years ago.  If Medicaid no longer provides transport call the taxi company and see if they will drive you and get assurance from the driver he will pick you up.  You need to have the test.    

No calling Craigslist.

I've had colonoscopies, and they insist you have someone looking after you the night after. (As per JustAsking's post). If that's not possible, you are stuck in hospital until social services can organise a care package.  This post was edited by Malizz at July 15, 2018 4:32 PM MDT

Don't use Craigslist....that is dangerous. 
Talk to your Doctor and explain. You will likely have to stay the night in the hospital so they can watch for complications.