According to the IRS, your mother is the nominee. Per https://www.irs.gov/instructions/i1099gi#:~:text=Generally%2C%20if%20you%20receive%20a,the%20amounts....
A. Who Must File
See the separate specific instructions for each form.
Nominee/middleman returns.
Generally, if you receive a Form 1099 for amounts that actually belong to another person, you are considered a nominee recipient. You must file a Form 1099 with the IRS (the same type of Form 1099 you received) for each of the other owners showing the amounts allocable to each. You must also furnish a Form 1099 to each of the other owners. File the new Form 1099 with Form 1096 with the IRS Submission Processing Center for your area. On each new Form 1099, list yourself as the “payer” and the other owner as the “recipient.” On Form 1096, list yourself as the “Filer.” A spouse is not required to file a nominee return to show amounts owned by the other spouse. The nominee, not the original payer, is responsible for filing the subsequent Forms 1099 to show the amount allocable to each owner.
