It scares me that she wants my son. What shall I do?

My husband's colleague's wife cannot have children and were thinking of adopting a boy. I just had my son 7 months ago, we met my husband's co-worker (who I knew a long time) but his wife. They came over for my husband's birthday two weeks ago with a couple of friends. I offered his wife to hold my son, and she said "oh he's perfect, I really want him" she added "if you're thinking of adopting let me know" I was angry she said that. Her husband was like "Ruth, that's not fair, it's very impolite". The more she sees my son, she overtakes me and looks after him instead. Her husband says "you can't do this" but she said "he's perfect, I really want him". There's so many kidnapping I'm scared it will happen to me. Kidnapping happens within close friends and family too you know, you don't know anything.