Ok, I'm doing more work on some specifics. Please let me know if my info is any good.
"Alice" is phonetically close to "Ellen," and it may be that I need to "listen" more patiently to my impressions. But I still feel there's an "Ellen" in the picture, and that she is on the other side with your mother. This would be a sister or friend of your mother's which is an aunt in relation to you-- or possibly she's your grandmother.
For the departed niece, I get a "D" name, like Denise or Desiree. Or maybe that's my mind playing word games with me: "Denise the niece."
I asked Alice to show me some things. Let's see if she did. The very first thing to come through was that there was something in the past between you and your sister and that you should "get over it." Not as if to say you were wrong or your sister is right, but that you have to let go of it. This goes way back to high school (I see lockers). It's something about some gossip or slander your sister spread about you, and if this is indeed your mother talking, she says "get over it." Do you know what this is in reference to?
I asked how your mother died. I got some confusing pictures. There was a car, and so naturally I thought, car crash? Then there was a can of sardines. This, to me, means crowding. It seems as if a crowded commute took a toll on her nerves. I think a cardiovascular problem took her life. Something about electrolyte imbalance. Did she experience fibrillation or tachycardia?
I asked when this occurred and got a 7. If this means 1997, then this is longer ago than I previously thought.
There was something about the funeral. I saw a picture of a little girl holding her mother's hand. It reminded me of pictures of Jackie Onassis and her daughter at JFK's funeral. I am trying not to analyze this image, hoping that it means something as is. But if I had to, I would guess that it's an image of your niece who died recently.
I think that my reading here is probably too "front-loaded" with info you've given, but we'll see.
Edit: Looking back in this thread, I see your sister was only a teenager when your mother died-- probably too young to have had a daughter by then. Your mother couldn't have been very old when she passed.