Gold digger targeting father?

So what do you do when there maybe a parasite attaching to a vulnerable old man. My father fairly recently lost my mother and now is hooked up with someone who maybe directing him to financial ruin. He is emotionally vulnerable and needy so he is a perfect target for a predator. However, his financial woes may in large part be of both their making. I get the feeling neither one of them can handle money well. Since they have not come to me for money, I think I should just ignore what I hear. However, my father has made comments to my sister that seem to indicate he is done with life, and this worries me. I am the family hard *** who is quick to throw the bullshit flag. I also am very financially disciplined. Because of this reputation he has all but avoided me. He is somewhat timid in someways, and has lost his advocate, with the death of my mother. Should I just stay back and say nothing or step up?