I can only speak to US taxes. You will have to consult India for rules on how she needs to do her taxes there.
The filing requirement for persons over age 65 is $14,050 as you mentioned. If her income is less, she does not have to file. Income from stock trades is investment income, not self-employment. Unless she meets the very stiff requirements to be considered a day trader, which is doubtful, she does not have SE income.
