そぼ
grandmother (my own)
sobo
JMdict 1396860
祖母(そぼ)のgrandma家(いえ)houseに行(い)くgo
Going to grandma's house
の ('s) links two nouns to show possession or belonging — 祖母(そぼ) (grandma) + の ('s) + 家(いえ) (house) means “grandma's house.” Then に (to) marks the destination of 行く(いく) (go): the direction you're heading.