A division bench of Justice B N Sinha and Justice Shivaji Pandey granted the bail to Pathak, who is serving life sentence in Beur jail in Patna.
The court granted the bail after taking note of arguments by Pathak's counsel while challenging her conviction in which he had expressed doubts over authenticity of the knife being the same that was used for the murder and the two-day delay by the police in filing the FIR in the case.
Designated CBI court judge B N Singh had awarded the lifer to Pathak on April 10 last year after finding her guilty under section 304 (culpable homicide not amounting to murder) of IPC.
Keshari was stabbed to death by Pathak at his residence in Purnia district on January 4, 2011.