Right answer:
nunca
Nunca is an adverb of time. Adverbs of time give information on time, duration, and frequency answering questions like When? and How often? Recall that an adverb is a word or group of words that describes or modifies a verb, adjective, another adverb or a whole sentence. The other words nada means nothing and nadie means no one, so these can't be the answers. Finally:
No voy nunca al estadio (I'm never going to the stadium)
