I think she should convert most of her money into cash or bonds. Losses in the past should not affect what you do now. This is the sunk cost fallacy.
Some people claim that by shifting assets from shares to bond you are locking in past losses. This is not true. When the value of the shares went down, you have already lost the money.
It is true that by switching from stocks to bonds you make less when or if there is a recovery, but we cannot say whether there will be a recovery soon or not. If your mother needs the money to survive, it's better not to take the risk, otherwise her balance might fall to, say, $100,000 and she may not be able to live off that.
Just because stocks are down from the highs they were a year ago it doesn't mean they are less likely to go down. Stocks may have a while to go down. In the last ten years the S&P500 has not increased. In the last 18 years the Nikkei 225 has gone down by 70 per cent. This means the stocks markets of the two largest economies have shown sluggish performance in the long run.
It seems as if your mother is living off dividends. She doesn't need capital growth, so she never should have had her investments in growth stocks. I recommend moving the money into yield investments like dividend-paying stocks, bonds, property, money market, etc.
As a rule of thumb, the percentage of your portfolio you should allocate to cash and bonds should be your age. For example, if you are
60 years of age, allocate 60 per cent to cash and bonds.
Even if stocks do recover, if she had 40 per cent still in stocks, she captures that recovery to some degree.
Be wary of the gambler tendency to win back losses. That lost money is gone.
You should see a financial adviser for more specific advice related to your situation, but be careful about whwat kind of financial adviser you see.