There are some very good second-tier accounting firms also, but the Big 4 are a great way to start a career. I was a partner in a Big 4 firm and know a lot about them but not so much about finance degree opportunities. I think a lot of it should come down to whether she is more interested in finance or accounting.
The nice thing about auditing is that you deal with pretty high-level executives in organizations right away and you see the inner-workings of numerous companies and often industries. There are also many opportunities within the Big 4 in other departments, locations, etc. Typically the Big 4 only recruit those with very good grades, at least that is the way it was quite a few years ago when I started.
For what it is worth, I started with a Big 4 firm in the US, transferred overseas and worked with them, changed to a different Big 4 firm and ultimately was able to retire at 40 and move back to the US, so there is money in accounting, as well as finance, although I was in the right place at the right time…