Step 1: Understand the problem.
Under the Code of Civil Procedure, 1908, a plaintiff fails to pay the required court fee or postal charges for serving summons within the time the court allowed. We must find what the court may do.
Step 2: Why does the fee matter?
A plaint must be properly stamped with the correct court fee. If the fee is short and the plaintiff does not make it good in time, the plaint is defective and cannot proceed.
Step 3: Apply Order VII Rule 11.
Order VII Rule 11(c) says the plaint shall be rejected if it is insufficiently stamped and the plaintiff, when told by the court to supply the fee within a fixed time, fails to do so. Rejection of the plaint effectively ends the suit.
Step 4: Add the summons angle.
Order V deals with service of summons. If the plaintiff does not pay the postal charges needed to serve the defendant within the time allowed, the court may dismiss the suit for failure to prosecute it.
Step 5: Match with the options.
Both routes lead to the suit being thrown out. Among the options, dismiss the suit captures this outcome. So option B fits.
Step 6: Eliminate the others.
Option A (return for fresh presentation) applies to wrong jurisdiction, not unpaid fees. Option C (stay until service) is not the prescribed consequence. Option D (decide on merits) cannot happen when the plaintiff has not even paid to move the case forward. So A, C, and D are wrong.
Step 7: Final answer.
\[ \boxed{\text{Dismiss the suit.}} \]