Things to consider in regards to accepting a large monetary gift

Long story short, I have a close family member whose spouse was a member of an esteemed military group many years ago. Shortly before their 20 years in the military and with young children at home, he fell ill with brain cancer. He was never the same and of course could no longer provide for his family. He died a few year back and his wife now gets by with SS, Medicare, and I assume some other related government funds. Most of the guys in his group went on to live out long, successful lives. 1 wealthy member has anonymously reached out and wants to gift the surviving wife a large sum of money. She has many concerns and I'm trying to help her develop a list of both the positives and negatives and just any considerations in general. Appreciate your help.