The correct option is B Imperative Mood
Mood is the mode or manner in which the action denoted by the verb is represented.
A verb which makes a statement or fact or asks a question, or expresses a supposition which is assumed as a fact, is in the Indicative Mood.
A verb which expresses a command, an exhortation, an entreaty or prayer, is in the Imperative Mood.
The Subjunctive Mood is used to express a wish or possibility.
The verb in the given sentence expresses a prayer. It does not state a fact or a possibility. So, 'have' is in the Imperative Mood. Hence, Option B is correct and the other options are not.