Step 1: Understanding the Concept:
The question asks to describe the concluding mood and imagery of Walter de la Mare's poem 'Martha'.
Step 2: Detailed Explanation:
The ending of the poem focuses on the lasting effect of Martha's storytelling. The final lines describe how, even after her voice has faded, the atmosphere she created persists.
"And her beauty far away
Would fade, as her voice ran on,
...
Our hearts stood still in the hush
Of an age gone by."
This ending emphasizes that the experience was not just entertainment but a deep, emotional journey into a timeless, magical world. The mood is one of peace, nostalgia, and gentle melancholy.