It is on her end to provide the documents at a local US consulate where she lives, but for a B2 visa, the primary concern when they call her in for an interview is to show she has sufficient ties to her home country, she is only coming to visit, and she will return after her holiday. (in other words, she has no "intent to immigrate"). Here is a list that the Department of State provides:
Each applicant for a visitor visa must submit these forms and documentation as explained below:
Online Nonimmigrant Visa Electronic Application, Form DS-160. Visit our DS-160 webpage to learn more about the DS-160 online process.
A passport valid for travel to the United States and with a validity date at least six months beyond the applicant's intended period of stay in the United States (unless country-specific agreements provide exemptions). If more than one person is included in the passport, each person desiring a visa must make an application;
One (1) 2x2 photograph. See the required photo format explained in Photograph Requirements.
Good luck and if you have further questions, consider hiring an immigration attorney to make sure she isn't denied.
The answer above is for informational purposes only and is not intended to provide legal advice or form an attorney-client relationship. The above response should not be relied upon for any specific situation. If you need legal advice specific to your needs, you should consult with a licensed attorney.
I would recommend hiring an experienced immigration lawyer to help you draft a strategic "Letter of Invitation" for you to submit on behalf of your mother. In addition, a skilled lawyer can help your mother identify and organize evidence of nonimmigrant intent and prepare her for the visa application process/interview.