This is NOT her child anymore. This is NOT he son. She gave birth to him, but HE IS NOT HERS. She has NO legal rights. She can't just request the child "back." This child is solely, legally the adopted father's child. She gave up her right to parent, when she willingly handed her child to someone else, and they adopted him. There are no take backs.
This story stinks and is VERY fishy. She GAVE UP her own child, because someone else couldn't have any? Really? You just hand it over, like there is no love, no bond. Here ya go!! A MOTHER is going to hand over her toddler, out of the goodness of her heart? NO, I don't believe that for a second. She probably got the child taken away (or there was the threat) and now she wants a do-over. She needs to leave the child alone. He IS NOT HERS. She doesn't get to have an opinion on how he is raised. She GAVE UP that right. His mother just died. The father's wife just died. Now she wants to sweep in, because she doesn't approve of how the child is being raised. Guess what lady, you don't get a say. You gave your child away like a freaking puppy. Do you really think the child would be better with a woman who handed him away like an object, and "wants him back" him now that his REAL mother has died? Like she let a friend borrow a sweater, or something? What a bottom feeder.
Your co-worker is either a liar, a sorry excuse for a mother, a horrible opportunist, or worst. Who does that? An AWFUL person, that's who. Don't believe what she is saying, and don't give her any advice. Her story is shady, at best. Stay FAR away from her.
Oh, and what kind of person openly admits to co-workers they just handed their toddler to someone else? She is messed up, for sure!! My advice for her? Get therapy. And, don't GIVE YOUR CHILD AWAY, if you want to have in opinion about their lives. A birth "parent" only has rights, if they keep their rights. She handed them away.
ETA: Since you asked, if she really did seek to get this child back...she is completely morally bankrupt. I don't care how you defend here, for her to think about it, is even wrong. For you to defend her, is also wrong.