They're travelling at the end of the month? As in, in less than four weeks? And applying in the UK for someone that isn't a UK national? You believe in cutting it fine in terms of timing, don't you?

More to the point, why a B1? It's a trip to the US for the carer and the person being cared for? That isn't B1 material unless the employer is a US citizen and/or the employer intends to stay in the US.

If they are both simply visiting then a stock WB visa waiver app via ESTA is sufficient for the carer, assuming she's from an eligible country.