The correct option is
B Aparna and Namita are my friends.
The given sentence is an assertive or declarative sentence. Hence, it has to end with a full stop. As the words, 'Aparna' and 'Namita' are proper names, the first letter of these words should be capitalized. As the word 'friends' is a common name, the first letter of this word should not be capitalized.
Option A is incorrect as the letter 'n' in 'Namita' is not capitalized and the letter 'f' in 'friends' is incorrectly capitalized.
Option B is correct as it is punctuated as per the rules mentioned above.
Option C is incorrect as the letter 'n' in 'Namita' is not capitalized. Further, the sentence wrongly ends with a question mark instead of a full stop.
Option A is incorrect as the letter 'n' in 'Namita' is not capitalized and the letter 'f' in 'friends' is incorrectly capitalized. Further, the sentence wrongly ends with an exclamation mark instead of a full stop.