Maybe just call her let her know you care but can't make it. No mother will be mad that you chose not to drive out when not well. On the financial issue is there any local places that can help? Or places online like gofundme etc? We all struggle financially at one point in life there are places generally that can help to a point. Wish u both better don't do the trip sick and instead wish your mother well and look into such things for her instead of driving when sick. Hope that helps get better soon.