The sentence "Je souhaite que vous __ beaucoup d'argent" requires the subjunctive mood because the verb souhaiter (to wish) expresses a desire, and in French, souhaiter que is always followed by the subjunctive.
The meaning of the sentence is "I wish that you have a lot of money." The verb needed is avoir (to have) conjugated in the subjunctive for vous. The subjunctive forms of avoir are:
que j'aie
que tu aies
qu'il/elle ait
que nous ayons
que vous ayez
qu'ils/elles aient
The correct answer is therefore ayez.
The other options fail for clear reasons: soyez is the subjunctive of etre (to be), which does not make sense with "beaucoup d'argent." Ai is the indicative first-person singular of avoir - wrong person and wrong mood. Avons is the indicative first-person plural - also wrong person and wrong mood.