In the above sentence, the word 'still' adds to the meaning of the word 'lives'. It tells us 'He' is presently living in that house. Since 'lives' is a verb so the word qualifying it or adding to its meaning will be an adverb. Therefore option A is the correct answer.
An adjective is used to add meaning to a noun or a pronoun. In the above sentence, 'still' does not add any meaning to the noun in the sentence which is 'house' or the pronoun 'he'. Hence, option B is incorrect.
Conjunction is a word used to join words or sentences. 'Still' in the above sentence does neither therefore option C is incorrect.
Option D is also incorrect as 'still' is not the name of a person, place or thing as nouns are.