Hello,Thanks for your question.
If your mother has not given more than $1 million in her lifetime, she will not have to pay a gift tax because of the lifetime exclusion. However, even if no tax is due, a gift tax return, Form 709, would need to be filed by your mother since the amount given is over $13,000. The receiver of the gift does not need to file or claim any gift. The due date for Form 709 is the same as the Form 1040 deadline, April 15, after each tax year.
For reference, see Publication 950, Introduction to Estate and Gift Taxes
Hope this helps,Best regards,