其中大,小写字母变化是原文如此.从此信看,如果不能按时提供证明,申请就会被拒.
-Just respond to this REF that your mother did not extend her status during that period of time. Also justify in the resposne letter that your mother re-entered US using a new B2 visa recently and thus, her previous unlawyful presence should not affect her I-485 (this record should be removed automatically) and also emphasize that your mother is your immediate relative for her green card application and thus, any unlawyful presence (even if she has) should not affect her I-485 approval.
She will be fine and nothing worried about.