I'd second everything @Mathew said about Armadillo - it's a great product - but like most of the other offerings here it's Stacks-based.
I'd recommend you steer clear of the RapidBlog plugin. In its day it was a fantastic product that did a great job of integrating a Blogger blog pretty seamlessly into Rapidweaver. Indeed, it still works and I have it running on a few sites. But the developer has said he's unsure about Rapidblog's future, so at the very leas, approach with caution.
I think the easiest way to get a blog your friend can update is to use Tumblr and then integrate it into Rapidweaver using Will Woodgate's free MicroBlog stack. Unless she's doing anything fancy, I would have thought that Tumblr will be a good fit. It'll certainly handle text, photos, galleries and videos.
There's also RW Writer which has a small one-off cost and then a monthly subscription fee - or it did when Blueball sold it; now it's under the Yuzool banner there might be a slightly different pricing model. Yuzool also sells the Pulse CMS which has a built-in blog.
Like I say, for a quick and dirty - but effective - blog, I'd look at a Tumblr/MicroBlog combination, on the understanding that anything that relies on a third party to deliver the functionality is subject to that third party's whims.
If you want to control your own blog and store everything on your own server and still update it from anywhere, then I think Armadillo's a great choice.