What's her tax rate, 0%?
REITs are taxed at ordinary income tax rates for the distributions, and capital gains for the appreciation. Something like the Vanguard REIT ETF holds a diversified portfolio that has a very solid return. If she is basically paying zero income tax, it would be a special opportunity to get a nice return without tax. Of course, for all other investments she could be in the 0% capital gains bracket if she's in the 15% income tax bracket or lower. So she could have favorable taxes all around.
I would do something like a mix of 1/3 BND (vanguard bond ETF, ~2% yield) 1/3 VNQ (vanguard REIT etf ~3.5% yield) and 1/3 VYM (vanguard dividend etf ~3.2% dividend yield). These are all fairly low fee ETFs as its vanguard, but they aren't like the 0.05% fee VTI fund. Over a 3-5 year period, the difference from .05 to .25 fees isn't going to make a big difference, like it would on a 25-30 period.