'नी' धातोः ल्युट् प्रत्यये रूपं भवति-
English: नयनम् is correct dhaturupa lakara purusha vachana form according to Sanskrit dhatu conjugation rules. Hindi: नयनम् सही धातुरूप है जो लकार पुरुष वचन के अनुसार बनता है।
Ref: NCERT Sanskrit Class X Dhaturupa explains lat lrit lot vidhiling lakara purusha vachana dhatu forms with examples clearly.