I think it's 'la' but you might want to wait and see if someone agrees with me
Answer:
1. Janet y Andy son los amigos.
2. Luis y Carmen son los padres de Marisa.
4. La mama de Luisito es Carmen.
5. Marisa es la hermana de Xochitl.
6.Luisito es el hermano de Xochitl.
in the second picture doesn't say the relation between them so I didn't know the answer for number 3
