How is the au pair here legally?

Is A Brazilian by any chance? There's a big network of Brazilian au pairs in the DMV, and a lot of them work out ways to stay after their visas. At least one I knew of was in a green card marriage.

I hired one as a baby sitter once, and ultimately had three women from the "network" work for me for occasional sitting or back up care. They were hands down the best nannies I've had, and if I had ever been hiring when one of them was free, I would have snapped her up.

None of them ever asked me about a rate or anything, and I know one of them was being badly taken advantage of by her family, who was relying on her for a lot of free extra care. But she did it happily because she loved the kids.

Anyway, if Ana is a Brazilian au pair, I believe the story and would definitely pursue it at least a little further. And make her a good offer.

No, I don't think it is a red flag that B isn't asking you about any job benefits as of yet.
Perhaps she isn't expecting any, she may not have had them offered to her in past positions after all.

Why not take the initiative & go ahead and offer them to her yourself upon hire??
She will be grateful unless you are hoping she won't ask so you can save a few dollar$......

Yes, it is quite odd that A's former Au Pair mother is not returning her calls. Huge red flag!!

Either A was not a good Au Pair or perhaps A was never one to begin with.
I was under the impression that Au Pairs were from other countries and usually left the States once they complete their work.
Why can't A contact the agency she worked with??
I smell a rat and would discourage hiring her until you speak to a few people.

B sounds fine, but my hunch is that she doesn't plan on working for you long-term. She probably really needs $$ right now so she will work for a lower rate until she can find something better paying along the way.

I advise you to offer more than $10/HR in order to have access to a better pool of potential nanny candidates.

So concisely, what are you asking?

I posted a job online in care.com and got many replies. I liked one person, let's call her "Betty" and was about to give her an offer.
But then, this other person let's call her "Ana" or "A" got back to me. Weeks ago, I liked her profile, had messaged her asking if she'd be interested in a full-time job. She left a good impression during the interview but didn't ask me about vacation, holidays, sick. She was talkative but she didn't ask me any questions at all. She's not a shy personality and she has au pair and PT babysitting experience.

Is the only way to truly gauge interest to offer her a job and see if she starts adding conditions or asking details? I'm concerned that because the start date is not for more than a month later that she might change her mind if she finds something better. I'm nervous t because my rate offer is on the low side and she's one of the better qualified people I've interviewed.

The others I interviewed were people who sought me out due to my job posting so they took the initiative. The reason I'm seeking guidance here is because I don't want to lose "Betty" either while pursuing A. I want to get a reference from the au pair mom but I'm told she's not replying to "A" as of yet. I can't wait a few more days without starting to give B the impression she's on the back burner, since I already spoke with B's references.

Separately, is it a red flag if the au pair mom never gets back to "A"? "A" worked for her as recently as last year, but the reason I was given by A that Au Pair Mom is not a reference was that the nanny had more recent references, that au pair mom reference was from the past. Maybe the au pair mom can't highly recommend "A"? Would you skip talking to au pair mom and give "A" the offer?