Sanjeev stayed at work _______ he could complete the pending work.

so that

Sanjeev stayed at work so that he could complete the pending work.

• "In spite of" suggests that Sanjeev stayed at work despite some difficulty or obstacle, which is not implied in the sentence.
• "Meanwhile" indicates that something else happened while Sanjeev was at work. This doesn't convey the intended meaning of the sentence.
• "Although" suggests a contrast or concession, which is not relevant in this context.