Two short stanzas, and a small shift of attention. At first the speaker's mind is busy with errands, the everyday to-do list. The comparison to a "doting comb" is gentle and a little funny: the chores keep tugging through the mind the way a fussy, affectionate hand might keep combing the same hair. They are not cruel or heavy, just constant.
Then the speaker lets all of that go. "Let all be forgot but this ridge" reads like a wish or a quiet command, and the poem narrows to one place. The ridge is also called a "former peak," which suggests something worn down by time, no longer dramatic, but still there and still solid. The speaker seems to find calm in that humbler, older landscape.
The mood is peaceful and attentive. The title, "Presence," fits: being fully where you are, with worries falling away. The poem doesn't explain this feeling. It simply lets the ridge take over the mind.