Neither are right. The first one should not have "arimasu" for living beings, and the second says "I need (my) older brother and older sister" The correct way to say it is to say "私は兄と姉がいます。"watashi wa ani to ane ga imasu", which means "I have an older brother, and an older sister."

both sounds improper. 私には兄と姉がいます。 is the right way to say that. Also... 「うちには犬がいます。」 = 「私は犬を飼っています。」 = I have a dog.