Ditto to what Dolly said, And at their age they may never "get it" about addiction and continue to be vulnerable, so maybe a family meeting may be appropriate to make sure he never has access to their money again.
Normally I would tell you to let them all sort this out, it's not your stuff, but old people are helpless as children sometimes and I think they need protection too.
Sorry for the circumstance but glad to see you back Rozied.
Hugs