You need to start with a price range, as that will narrow down the choices a lot. Personally, I think it's better to purchase separate sewing and embroidery machines as then you can be sewing while the embroidery machine is working; however, that may be out of the current price range.
If her budget is really tight, I would look at the machines at Walmart. One good thing about Walmart is that if you try out the machine and don't like it, they will take it back. Dealerships typically will not take a machine back, but will allow you to "trade up" into a more expensive machine.