How is the underlined pronoun in the sentence used?
sandy showed them her coin collection.
a.
subject
b.
direct object
c.
object of a preposition
d.
indirect object

It should be A , because sandy is the pronoun

1 Sandy showed -them- her coin collection. 
Ask "what is the verb?" Showed. 
Who showed? Sandy, that's the subject 
Sandy showed what? collection, direct object 
Sandy showed collection to whom or for whom? them, indirect object 

2. Possessive, it tells you whose collection it is. 

3.Direct object 

4. object of the preposition, among us is the prep phrase 

5. me; obj of the prep, "Between you and me" is the prep phrase 

6. her, indirect obj., It's her because if Danny wasn't there, you would say "they gave her permission" 

7. We, subject. I know this sounds weird to say it this way, but its just a strangely structured sentence. If it read "We are the ones who did it," then you would see it easily.