My husband was 18 when his mother passed. I meet him, in 93 and we married in 94. I use to smell an unfimilar perfume and sense her presence often. I talked to her. When she was comfortable with me and knew that her "baby" was in good hands, she left. It made me very happy, to know that she liked me and trusted me with her most precious gift, her son.
One other thought, do you have children still living at home? If so, she may be there for them as well.