Answer:
consonance
Step-by-step explanation:
Assonance takes place when two or more words, close to one another repeat the same vowel sound, but start with different consonant sounds. Vowels are different in moth-thither, there is no assonance here.
Alliteration happens when two or more words include the same consonant sound at the beginning of the word. Moth does not begin with th, so there is no alliteration here.
Consonance is the repetition of a consonant sound and is typically used to refer to the repetition of sounds at the end of the word, but also refers to repeated sounds in the middle of a word. So the answer is consonance.