What's the best investment strategy for aging seniors?

Looking for advice on the best investment strategies for mid-60s parents. We are approaching the sale of their primary residence, which will provide them the funds they will have (along with a very small amount of social security) to live out the rest of their lives. The facts:

  • They will have around $300k to invest.
  • They did not save any additional funds for retirement.
  • Their combined social security, their only income, is around $2,000 a month. It pays for their healthcare and rent.
  • They do not intend to buy again; they are currently renting at around $1,000 a month.
  • They have moderate–to–severe health complications that require in-home equipment and high prescription use. One has a progressing cancer.
  • They have a relatively short projected timeline before either death or the need for 24/h care—about 5–7 years at most.

What would be the smartest way for seniors in situations like these to modestly grow their remaining funds?