The correct option is
B I was accused of stealing money.
The given sentence is in active voice as the subject 'Somebody' performs an action 'accused' against the object 'me'.
To
change to passive voice, the object takes the place of the subject and
vice versa and the verb form of the sentence is also changed from active
form to
passive.
'Subject (Somebody) + verb (accused) + object (me) + prepositional phrase (of stealing money)' changes to:
'New subject (I) + verb (was accused) + prepositional phrase (of stealing money)'
This can be seen in option C, hence it's the right answer.
The pronoun 'somebody' is indefinite; it does not refer to a particular person. Hence in passive voice it can be omitted and instead implied.
Option A: The verb form 'am accused' expresses the simple present tense whereas the sentence is in simple past tense.
Option
B: The clause 'somebody accused me' is still in active voice and by changing the position of 'stealing money', the sentence is left incomplete.
Option D: The verb form 'am accuse' is grammatically incorrect as 'accuse' is a base verb and must be conjugated according to the required tense form.
Hence options A, B and D are incorrect.