Ignoring who's to blame, it looks like you were not involved in the collision and that the accident was between the old woman and the woman that ran into her. So the fault is with either of them.
Its not quite that simple - you can cause an accident whilst not being involved yourself. But in this case you were on the pavement with the door shut and your car parked between two others. Assuming you werent parked on double lines or causing an obstruction I cant see how you could be involved.
However the law is unpredictable and not always rational. If you find yourself legally involved dont forget to claim whiplash. You looked round at the noise so fast that your neck hurts. ;-)
