Explanation:

- The original sentence reads, "Kanika shall be grateful to you if you (are of help) her now." The phrase "are of help" is somewhat formal and outdated.

- Option 1: "help" - Using "help" makes the sentence more direct and modern. This is the correct replacement, creating, "Kanika shall be grateful to you if you help her now."

- Option 2: "shall help" - This option incorrectly suggests a future action rather than immediate assistance.

- Option 3: "would help" - This creates a conditional clause that changes the meaning slightly, implying a hypothetical situation.

- Option 4: "no improvement" - The original phrase is less common in conversation.