I can't stress the importance of the psychics and foreshadowing on the show. I think it's easy enough to pass off the psychics as creepy and not advancing anything, but trust me there is a story to be told if you pay attention to the dialogue.
The most underrated scene involving Mrs. Grunwald is her introductory scene on PLL when she talks to Toby & Spencer in Ravenswood. What's so brilliant about this scene is that even though she was lying the entire time, it was enough to reveal the truth. The whole idea about her dialogue with Spencer was a gigantic clue: the opposite of what she said is the TRUTH. Why is this so brilliant, because she may have just revealed the identity of the "he" who was after Ali.
Spencer: "You still know this person."
Grunwald: "I didn't know her alive. I certainly don't know her dead".
Spencer: "Maybe you only spoke with her on the phone. She might have gone by the name Vivian. She though that somebody was after her. So maybe she was asking for help or a place to stay."
Grunwald: "I'M SORRY, IT DOESN'T RING A BELL"
Camera changes to Toby who looks alarmed by the comment and immediately gives Mrs. Grunwald one of his creepy stares. Notice anything else? She never makes eye contact with Toby(the entire scene).
Spencer: "The girls said that you disappeared everyday for hours at a time...blah...blah...blah..."
Notice what Toby does the rest of the scene. He reexamines the photos of this woman. Did she discover a secret of his?
Grunwald's last line: "I'm very sorry about your friend, really. But I can't help you. I'M NOT WHO YOU THINK I AM."
Toby gestures over to Spencer leave. Did anyone catch that besmirching look Grunwald gave when they walked out the door at the end. I wonder who that was directed towards
Next Spoby scene:
Spencer: "She would rather fry off the top of her head than talk to me."
Toby: "SHE MAY BE TELLING THE TRUTH"
Spencer: "She's not"
More Toby lines(not in order): "We have to face facts, you're following a lead that came from a bird. Maybe it was never a real clue. YOU HAVE TO LEARN WHEN TO LET THINGS GO SPENCER." Toby's trying to deflect Spencer from further investigating the truth
Spencer:"Me, I need to learn to let go. I may be trusting a bird but you're trusting A." He deflects yet again
Knowing what we know know, I think Mrs. Grunwald gave us enough insight to go on to make direct links to the past & future at the time of that scene. She already established later in season 4 that one of them has been touched by the one Ali fears the most. Someone close to the liars is not who they say they are. The bell clue: Is Grunwald hinting that it was Toby who pushed Ian off the church bell tower?(it definitely got his attention). Toby was also the first person to identify Charlotte's body at the church bell tower. Did he kill her or was perhaps involved in her cover up. We don't know the answers to why or how Mrs. Grunwald seems to know things and appear at the right time when the liars need help. The fact that the writers keep bringing her back into the story shows that she is relevant big time with the whole psychic and foreshadowing theme of the show.