Archivo:Isobel Randolph Fibber McGee and Molly.jpg

• No copyright marks are seen on the photo.
• link 2 (no wayback machine due to robots not allowed above)

and another version of the photo that depicted only Jim and Marian Jordan:

photo front

photo back

• From the list of supporting cast and their photos, this appears to be circa 1939. Some characters shown on it were introduced in that year, while others who were introduced later in the run of the program are not pictured in the cast photo. The radio program aired from 1935 to 1959.
• The dating makes the item well within the pre-1978 timeframe.
• United States Copyright Office page 2 "Visually Perceptible Copies The notice for visually perceptible copies should contain all three elements described below. They should appear together or in close proximity on the copies.

1 The symbol © (letter C in a circle); the word “Copyright”; or the abbreviation “Copr.”

2 The year of first publication. If the work is a derivative work or a compilation incorporating previously published material, the year date of first publication of the derivative work or compilation is sufficient. Examples of derivative works are translations or dramatizations; an example of a compilation is an anthology. The year may be omitted when a pictorial, graphic, or sculptural work, with accompanying textual matter, if any, is reproduced in or on greeting cards, postcards, stationery, jewelry, dolls, toys, or useful articles.

3 The name of the copyright owner, an abbreviation by which the name can be recognized, or a generally known alternative designation of owner.1 Example © 2007 Jane Doe."