at 70 I wouldn't invest in anything risky. Stick with bonds, CDs or other short term low risk investments. I know the stock market looks appealing to many right now but we are at all time highs, now is not the time to buy into the market with large sums of money, there is a high probability of a large market correction in the next few years IMO. Recessions are typically every 7 years, the last one was 08-12' so we are ready for another.
Honestly she might just want to stay with a large cash position, given the massive amount of consumer debt, record market highs, sales numbers of residential property, auto loans, student loan debt, etc... we are heading back towards 2008 bubble numbers. 70 year old women and soccer moms talking about investing is the canary in the coal mine. You want to buy when there is blood in the street, when people hear the words "wall street" and they get furious/scared s**tless that's when its time to buy.