I like the idea of telling her verbally, or better yet writing in an email, how much you appreciate her efforts. Perhaps you could even make it into something that could be put in her permanent file, and of course when the time comes for her annual review (if applicable), make sure to praise her there as well.
I also like the idea of encouraging her to find some kind of work-related opportunity, like a conference or extra training. Basically, something that is available to anyone, but managers usually don't like to fill out the paperwork/approve the time off/etc.--so you're telling her that if she finds something work-related she wants to do, you will go through the effort to make it happen for her. Even if she never does, she may find it meaningful that you sincerely offered. I was going to suggest that this could also apply to work-related equipment/supplies, but I see that she works from home and you're already suspicious of her husband taking/using stuff meant for work, so that might not work as well.