First off, I just want to say that I don't personally know if there are such books or other materials. You're probably disappointed. You could do a search on the Web, ask around like you're doing here, but I'm guessing there isn't much, and if there is something that's been done, you may not come across it unless you have contacts. That being said, I hope you do find something and I'd love to know what you find.
I used to be entirely in academic ESL but currently am doing work-related ESL (working with maintenance workers, restaurant workers, hotel banquet servers). Since food preparation is a huge field, I did find a few ESL materials for the latter two jobs, but after seeing a sample page or two from them on the Web, I opted to save my money and just make my own materials, as the ones I saw weren't really appropriate for my level of student or didn't exactly match what I wanted to do. When I started teaching maintenance workers, I didn't find anything at all. Maybe there is something out there, but I couldn't find it. At least nothing I could purchase; maybe a community college has a curriculm/materials they've developed for themsleves in that particular area of VESL, but I wouldn't have access to that. So, I've had to make all my own materials. Frankly, it's a lot of work. But I suppose you could find creative ways to lighten your load.
I would think teaching nannies would be really fun. You could teach them songs to do with the children, do a lot of TPR (Now change the diaper, now powder the behind

, etc.). If you don't mind sharing, where are you, who do you work for, and how did you get this job?
Good luck!