when the author realised , she was at the right -address ?

The narrator had initially thought that she was mistaken in coming to the right address. The fleeting glimpse of Mrs Dorling had not been enough to ascertain it really was her. She thought she might have rung the wrong bell but when she saw Mrs Dorling wearing her mother's green knitted cardigan, she knew she had come to the right address. The wooden buttons were rather pale from washing but she was sure it was her mother's cardigan and when Mrs Dorling realised this, she half hid herself behind the door. The narrator knew she had come to the right address.