The correct option is
B to gift
The verbs that do not explain the tense of the sentence and do not agree with the subject are called non-finite verbs. Non-finite verbs are usually infinitives, gerunds and participles.
Option A - 'Gifting' is the participle form of the verb. However, 'gifting' is a finite verb here. The verb in the given sentence is already in the participle form, hence we can't use another verb in the participle form. Hence, option A is incorrect.
Option C - 'To be gifting' can be used in passive voice. As the sentence is in the active voice, we can't use 'to be gifting' here. Also, it is grammatically incorrect to use. Hence, option C is incorrect.
Option D - 'Gifts' is the third person form of the verb, it is a finite verb here. It is grammatically incorrect to use 'gifts'. Hence, option D is incorrect.
Option B - 'To gift' is the infinitive verb, which can be used here as it doesn't explain the tense of the sentence. Hence, option B is the correct answer.
'We are planning to gift him a laptop.'