रात को माँ ने दरवाज़ा खोला और चाय बनाई।

At night, mother opened the door and made tea.

Breakdown of रात को माँ ने दरवाज़ा खोला और चाय बनाई।

• चाय: tea
• माँ: mother
• दरवाज़ा: door
• और: and

Questions & Answers about रात को माँ ने दरवाज़ा खोला और चाय बनाई।

Why is को used after रात in रात को?

Here को is marking a time expression, not a direct object.

रात को is a very common way to say at night.
So in this sentence, रात को works like an adverbial phrase telling you when the actions happened.

A few similar examples:

• सुबह को — in the morning
• शाम को — in the evening
• सोमवार को — on Monday

So को does more than one job in Hindi; here it is not the usual object-marker meaning.

What does ने do in माँ ने?

ने is the ergative marker. In standard Hindi, it is commonly used with the subject of a perfective transitive verb.

In this sentence:

• खोला = opened
• बनाई = made

Both are completed actions, and both verbs are transitive, so the subject माँ takes ने.

So:

• माँ ने = mother (as the doer of these completed actions)

This is one of the most important patterns in Hindi past/perfective sentences.

Why is ने written only once even though there are two verbs?

Because both verbs share the same subject: माँ.

Hindi does not need to repeat before the second verb if the subject is clearly the same.