Au pair scammers do not have a real au pair position to offer to anyone - the au pair position is invented, and the scam is to trick the au pair into paying for a non-existent visa and/or work permit; or for invented insurance, apartment rental, a contract, or flight costs; or to 'prove sufficient maintenance' by making a Western Union or MoneyGram transfer.
If your daughter has obtained a Working Holiday Visa for Australia in the normal way:
http://www.immi.gov.au/visitors/working ... ntries.htmhttp://www.immi.gov.au/visitors/working ... -apply.htmand has not paid any money to the host family, nor to any travel agent, lawyer, or immigration office which the host family directed her to; and has arranged her flight herself, or can confirm directly with the airline that her flight has been booked, it is unlikely that she is contact with a scammer.
If a fee
had been requested by the host family or by someone that they had put your daughter in contact with, it would be wise to investigate further, and we can usually recognise whether a host family is genuine or not from the email/s in which they describe their family and the au pair position.
What we can't do, however, is help to discover whether a real family is kind and dependable, or otherwise. Googling their email address and telephone number may lead to some further information about them, but, of course, some people do not have any 'online presence' at all.
Although I understand that you may not wish to seem as though you are supporting your daughter's decision to travel to Australia, for your own peace of mind, it may be best to have a chat on the telephone with the host family yourself, and speak to them about any concerns you may have - maybe your daughter would agree to this?
Also, do make sure that your daughter has access to enough money for hotel accommodation and a flight home, should she change her mind once there, and want to leave; and make sure that she feels totally comfortable about calling you at any time for any assistance needed.
I've removed the names of the host family from your first post, for their privacy, as there is no evidence at the moment that this is a scam.