Is your mother a US citizen living in Russia or is she a non resident alient?
First, no there will be no taxes due on the money she sends you. There may, however, be some reporting requirements, and they would be a little different if she were also a US citizen, which is why I asked that question.
However, if she is not a citizen, then you would need to file a Form 3520 with the IRS, ONLY if the amount she sends you in any one year is more than $100,000. If the amount is less than $100,000 then no reporting is even required.
If the amount does exceed $100,000, you would fill in Part IV of Form 3520 to report the amount of the money received. Form 3520 is just an informational form and is really for your own protection. If some years down the road you were wever to be audited for some reason, you would have a record of reporting the receipt of this money so there would be no question as to where it came from. But again, no taxes will be due regardless of the amount she sends you.
If this was helpful please press the Accept button. Positive feedback is also appreciated.