She can apply for a tourist visa- anyone can. I think the wait time for a B visa interview in MNL may still be the better part of a year, though. With a pending immigrant visa, it will be hard to show that she does not immigrant intent though.
She can only stay for as long as CBP allows entry. Wanting to stay for months could make them question how she can afford to do that, and whether she will go home, since she has demonstrated immigrant intent.