What feeling is suggested by the stamping and neighing of the horses when the morning comes? What contrasting feeling is suggested by what we are told about the traveler stanza?

I would assume dark, fearful, and gloomy. Like some is startling the horses as the morning come about.

The feeling that the speaker is suggesting in the third stanza is that though the traveler is dead but the life goes on. "the steeds in their stalls

Stamp and neigh," shows the readiness of the horses, that they are ready to move out of their stalls and to welcome the new traveler.

Explanation:

The theme of the poem is the ups and downs that one face in life but still the urgency to move on. We can see the glimpses of the life and death theme also as they are the intricate part of life's ups and downs. The stanza is telling that the traveler will not return as dead never returns.

"The day returns, but nevermore

Returns the traveller to the shore,"