Question

Mi hermano y yo ____ un DVD. A. Tiene B. Tenemos C. Tienen

Answer 1

(B) because its not proper grammar with a or c

Answer 2

Tiene is for singular words referring to "he/she" (doesn't include yourself)
Tenemos is for plural words referring to "we" (includes yourself)
Tienen is for plural words referring to "they"

Mi hermano y yo....is plural because there is more than one subject.
"yo"....it includes yourself

Therefore:

The answer is B. Tenemos.