Answer
In the Shastras (scriptures), the mention of Mrigachhala (deerskin) is generally found in the context of the seating of Rishis (sages), not of kings. Kings used to hunt; Rishis did not. Therefore, if deerskin is used in an Ashram, it is not appropriate to associate it with animal violence. In ancient times, forests abounded everywhere, and due to the abundance of forests, animals were also plentiful. Because of the vegetarian culture, common people and Rishis did not hunt them. Kings hunted so that their practice of archery (Dhanurvidya) would continue and their skill would be tested. Also, so that princes would not faint at the sight of blood, since much bloodshed occurs in warfare. Therefore, this limited violence was sanctioned for them. Due to the abundance of forests, deer and other animals would die natural deaths in large numbers. Accordingly, it was natural to remove their hides and fashion garments and seats from them. In fact, deerskin was used more for making garments than for seats. Therefore, it is not proper to associate every use of deerskin with animal violence.
In the Gita (6.11), while describing the method of meditation, Bhagavan says: "Shuchau deshe pratishthapya sthiramasanamatmanah | natyuchchhritam natinicham chailajinakushottaram" (Bhagavad Gita 6.11)
That is, the Sadhaka (practitioner) should establish a firm seat in a clean place, with Kusha grass at the bottom, deerskin over it, and a cloth on top.
In the Yoga tradition, it was understood that the Sadhaka's body should not remain in direct contact with the earth's moisture and electrical currents; hence the three-layered arrangement of Kusha grass, deerskin, and cloth was prescribed. In the present age, when forests have receded, animals and deer have diminished in number, and laws have been enacted for their protection, one may use a mat or yoga mat in place of Kusha grass, a woolen blanket in place of deerskin, and a cotton cloth on top.
How to make the Holika Dahan ceremony meaningful!
Tomorrow is Holika Dahan. On this occasion, may the Kripa (grace) of Bhagavan Narayana shower upon all of you, just as it showered upon Bhakta Prahlada!
The demon king Hiranyakashipu made his Vishnu-devoted son Prahlada sit in a fire alongside his sister, the demoness Holika, because Holika had a boon from Brahma Deva that fire could not burn her. Hiranyakashipu thought that Prahlada would be burnt and Holika would survive safely. But behold the power of Hari Bhakti (devotion to the Lord). The boon given to Holika was rendered false, and Holika was burnt to ashes. On the other hand, Prahlada sat fearlessly chanting "Narayana, Narayana," and the flames of fire could not harm even a single hair of his. This is the power of true Sharanagati (surrender) to Ishvara!
Therefore, on the day of Holika Dahan, in the morning, the worship of Bhaktaraja Prahlada should be performed: make a small symbolic image of him from clay or dough and worship it, and let all family members listen to his story based on the Bhagavata Purana (Seventh Skandha, the episode of Prahlada's life). Then recite the Vishnu Sahasranama before Prahlada ji, please him, and seek his blessings for Narayana Bhakti.
Then in the evening, the traditional Holika Dahan ceremony should take place. Hari Sharanam!