Complete the following sentence with the most suitable option:

 If he had more money, ________________. 

The provided sentence is a conditional of type 2. It mentions a hypothetical situation 'if he had more money and a likely outcome 'to help the poor.'

A type 2 conditional has the following structure: if clause (simple past 'if he had') + main clause (present conditional 'would help the needy' or present continuous conditional)

Option B: 'He would assist the needy' is a present conditional with the structure of type 2 conditional. So the option B is right.

Option A: 'Will help' refers to a future event and contradicts the type 2 conditional.

Option C: 'He will assist the needy' also mentions a future event.

As a result, alternatives A and C are incorrect.

Option D is incorrect because the solution is in option B.