If there is a group of people where there are only men, they should be referred to as "ellos". If there are only women, they should be referred to as "ellas", but, if there is a group of women and there is one man in the same group, even if the rest of the group includes 50 women, they should be referred to as "ellos". This is because the default gender of a mixed group (where there is more than one gender) is always masculine. You can always say "ellas y él", to include both and keep the respective genders if you want.

Well, in Spanish, if there are women and men in a group, we all use the masculine form. It means, your two female friends and you are together, we say nosotros somos amigos. Another example: In a class, there´re girls and boys and they´re all students, right? So we speak in Spanish like ¨Son alumnos.¨ I hope I make it understood because I´m not native Spanish speaker and I still keep learning. : )

In spanish we would say "somos amigos" using the male idea rather tahn the female because it is the way. If you say "somos amigas" and that includes you that would mean you are a woman what it obviously you aren,t. So, if there is a man in a group we always use the male connotation. I hope I,ve helped you¡