Probably won't get noticed, but this happened to my ex-stepbrother 10 or more years ago.
When I was around 13 my dad had taken a job in another state about 4 hours away. He would stay in an apartment there during the week and would come home on his weekends off. A couple of years later, my older stepbrother (around 17 at the time) began seeing what he claimed was an old woman around our local home. She would never do anything malicious, but she only presented herself to him. It would often be times when he was home alone.
This went on for a few months. Nothing more than the typical "what do you want" conversations. He said she would speak to him, most times saying that he was getting taller and mundane statements like that.
One night while me, my younger stepbrother, and stemother were visiting my father, we get a call from my older stepbrother. He was frantic tell my dad that he needed to get his hunting rifles out of his truck and lock them up inside. The odd part here is that my dad never left hunting rifles in his vehicle. At first my dad shrugged it off thinking maybe he had mentioned in passing that he left them there that morning. Then he started to wonder why he would be calling so late and why he sounded so panicky. While my dad went out to recover the guns, my stepmother asked what Brandon's (the older stepbrother) problem was. He said that the old lady had woken him telling him that Randy (my dad) needed to get the guns in the house. She apparently told him that if he didn't Brian (my younger stepbrother) was going to get hurt. After this my stepbrother never spoke of the old woman again. We assume she never came back.
tl;dr - My stepbro meets grandma the friendly ghost, who then heroically saves my younger stepbro's life.
A more heartwarming tale involves my ex-stepmother's mom. She was dying of lung cancer and while she was in hospice care, she would stare out the window and watch hummingbirds feed from a dispenser just outside the window. The day of her funeral a pure white humming bird hung around the flowers at the head of her casket for the entire service.