The Old Woman was a peace loving human. And, she had very definite ideas about right and wrong. And, oh my goodness could she keep a tirade going. Most often they were directed at me, and aimed at correcting that in me which she felt needed serious attention. (To be fair, monkeys are frequently naughty.) Even after I ventured away from their home, into the world, I would still hear her voice. I think humans refer to this phenomena as one's "moral compass."
Friends who have never met her, feel as if they know her as well as their own relations because of the stories and nuggets of wisdom I have stored up from her. I suspect a couple friends hear not only their own mother's voices but also the Old Woman's in their heads.
I mentioned that after she died last year, the Old Man took a picture of her that was probably 40-50 years old of her (interestingly, one taken when she was already a grandmother and not one of her as a young woman) and had multiple copies made of various sizes and had them framed and has them all over the house. I think my specific observation was that if any thing were to inspire her to haunt him, it would be the 16X24 framed copy of this picture that greets everyone as they come in the front door . . . and the many other copies throughout the house.
On my last visit, the Old Man gave me a 5X7 copy of this picture. He'd made several copies and was making sure everyone had a copy. I put mine on the fridge, about eye-level. It is comforting to have her "present" in my kitchen to go along with her voice in my head/heart.