Managing Tenancy-Related Issues: How to Handle Benefit Fraud Concerns

Hi All,
I need some advice. One of my tenants, who was in the UK on a company transfer, recently left the country after completing his job assignment. He stayed in the UK for about two and a half years.
Recently, I received some letters addressed to him, so I contacted him for a forwarding address. He requested that I scan and email the letters to him. While doing so, I noticed that one of the letters related “£125 cost of living payment” from the council, as he had been claiming Pupil Premium free meals for his daughter.
What surprised me is that he was earning close to £85K, and his wife was also working. At that level of income, is he even eligible for these benefits?
Can this be reported to the council, and if so, how should I go about it?
Thanks in advance for your advice!