Answer: Ellos
Step-by-step explanation:
The phrase "Mi mamá y mi hermano" involves two people, your mom, and your brother. Therefore, within Spanish, we would typically use "ellos" to describe a group of people, regardless if the group includes only males or is a mixture of both males and females.
It would not be "ellas" because it includes a person described as 'my brother' in the sentence, therefore the group is not solely made up of women (since ellas would describe a group of girls).
It would not be "nosotros" either, because that would be the English equivalent of saying "us". The narrator is not including themselves in this sentence, so the word "us" would not be applicable.
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