'I can think of one small gesture that might do some good. The mallorn trees of Lothlorien, thriving under the power of Galadriel and the care of the Galadhrim, inspire all who harbour love for the wilderness. The mallorns will resist stain as long as the Elves are here to tend them.
'I want you to go to my friend Menassiel in Lothlorien, at Cerin Amroth. Surely her heart will be move by your tale, as mine is. I would like to plant a mallorn sapling here, in this glade. It will give hope to the Huorns. I do not think it will fully quell their wrath, but it has been long since they have seen any light. They deserve a glimmer of hope, for someday the shadows of Dol Guldur will trouble this place no more.
'Go Menassiel now, Name and see if she will help you.'
The Elf Nifdir is moved by the unhappy state of the Mirk-hourns and the tale of their slow loss of hope. He wishes to do something to alleviate their sadness and despair.
You should speak with Menassiel and see if she will gift the Huorns of Mirkwood with a young mallorn, a light to dispel the shadows upon their wretched existence.
You should return to show him the seedling donated by Menassiel.