I'm so sorry that you have to deal with something so scary. Do you think your pdoc will talk to you over the phone if you aren't up to going out? I know he is very soothing when you talk to him, and maybe he can call in something stronger for your anxiety to help you through this

Is Alice aware that you don't have a ride home? She may offer if she knows you don't…
Asking for, or accepting, help from good friends may seem selfish, but sometimes they want to be there for you to help you through hardship.

Some states have transportation programs for hospital appointments, etc. I don't know if they do in your area, or your situation is appropriate, but if you have a social worker, asking may be worthwhile. She may have other ideas, too.

Also, does Robert drive? Or could you offer to pay Maria if she drives?