Is your mother a U.S. Citizen? Are you? Is your mother physically in the U.S? Are you?
Typically, there is no tax implication on "gifting" money to another person. However, if you give more than $15K to any one individual in a tax year, you are required to report it to the IRS. But still, *nobody* will pay *any* tax on the gift. To report it to the IRS simply file IRS Form 709 - Gift Tax Return.
Now the name of that form is misleading, as *nobody* will pay *any* tax on the money. But if the amount exceeds $15K you're required to report it. Additional reporting requirements "may" apply depending on the locale/citizenship status of the giver/recipient. But I myself am not cognizant to exactly what those additional reporting requirements may be.
Understand also that the IRS Form 709 has *NOTHING* to do with income taxes and is filed separately from any tax return.
See https://www.irs.gov/instructions/i709 for the actual form and instructions.
