If she's off, she's off. I would only email people who are off if they explicitly say they will be checking work email during vacation/off days. I suppose if it's an emergency I would contact them but not if they are at a funeral. I would figure something else out.

I'm not sure rush invoices that need be paid are considered emergencies or what they really are(sorry I know nothing about accounting). An emergency in my world is a client website is down and affecting millions of customers and/or we could potentientally lose a client over it.