Which of the following sentences could take the place of:
las profesoras dan información a ellos.
a) le se dan.
b) se nos dan.
c) se la dan.

The answer should c. Se la dan.
"Se" is the pronoun used to replace "ellos".
"La" is the pronoun used to replace "información". Información is female gender. You use "lo" for male gender and "la" for female gender.
And "dan" is, of course, the present tense of "dar".

-Letter a: the order in which the pronouns are located is wrong.
-Letter b: it's not "nosotros" but "ellos".

Bruno está hablando con su hermana

That is correct! good job!