The correct option is
B received
The given letter is an informal letter and we must fill in the second blank with the most suitable option. 'I have just...' explains us that the sentence is in present perfect tense. Let's find an appropriate verb.
Option A - 'Receiving' is a verb in continuous tense, and we need a verb in the perfect tense. Hence, option A is incorrect.
Option C - 'Getting' is a verb in continuous tense, hence, it doesn't grammatically fit in the blank. Hence, option C is incorrect.
Option D - 'Now receive' is grammatically incorrect. 'I have just now receive' is grammatically incorrect as, the verb is not in present perfect tense. Hence, option D is incorrect.
Option B - Yes, 'I have just received the lovely camera...' is in present perfect tense and is grammatically correct. Hence, option B is correct.