Gut--maybe your son can Skype with his dad if someone can set it up for Dad? Not as good as being there, but definitely could be better than nothing.
JohnnyK--at least you called your friend and didn't leave her hanging. If you didn't explain what was going on at the time if you are feeling better maybe it would be good to do so now...and set up another visit. From what you say this might happen again in the future, and then she'd be prepared. We all tend to blame ourselves if someone cancels on us, and to think our friend doesn't want to see us, and feel bad about it, so you'd be doing her a favor to let her know what's really going on--assuming you are close enough to her to feel comfortable doing that. And then there will be one more knowledgeable person there for you in the future.