Cos,
Are there practical things you can do?
You say rent a hotel room and car next year, why not this year? If you have comitted to staying with someone, why not at least a car?
For me, being able to "get out" is often key to getting through situations like the one you describe.
Also about your grandma, I believe in scheduling and then sticking to it like my life depended on it. So, agree when you will see her, make that as short as you can, and then go and do not even discuss longer options, off the table.
About the xanax, for me, does nothing, no light me up, nor does it make me more likely to drink. But you be you.
Now I am going to say the obvious because we love you - not drinking is the most important thing and if going, or staying, ever threatens that, you gotta go. Hotel room, early trip back, drive in the country, whatever. Your sobriety comes first, second and third -- grandma, your friend in recovery, the cousins, they all come behind always.
X