Mom revisiting after 3 weeks

[Md004]

My mom has a 10yr multiple entry visa..her last visit was for 2 months, she planned to be here for 6 months but had to leave because my grandmother passed away.Now she wants to come back after 3 weeks. Will she have any trouble coming back after such a short break? Also can she be say she wants to be here for 6 months or is it better she says she wants to stay for a shorter duration? What documents does she need to carry? Thanks!

[peace999]

I would advise against it.
She will definitely be asked the reason for such a quick revisit.
In the absence of a good explanation ( emergency), they can create hassles for her.
In theory a strict CBP officer can cancel her visa and send her back if it appears she is trying to stay rather than visit..
Why risk it if it is not very important.

Give it an interval of at least 4 months.