Peter’s mother-in-law’s immediate service to Jesus shows both her submission to Jesus as her Lord (see Matthew 8:8–9) and the complete return of her normal strength (Mark 1:31, Luke 4:39).
The suffering experienced by Peter’s mother-in-law prohibited her from serving Jesus, even when he needed her. After she was healed she therefore immediately proceeded to serve him.1
Someone who had a fever normally still remains weak for some time, yet Peter’s mother-in-law was immediately able to proceed to serve her guests (Mark 1:31, Luke 4:39). This showed that the moment Jesus touched her hand, she was healed completely in the sense that Jesus not only healed the fever, but also immediately took away all of the consequences of the illness completely.2
Her serving must also be understood as an act of gratefulness (see also Luke 8:2–3).3
Given that her recovery happened extremely quickly, she could immediately take up her homemaking duties again. The fact that it is here specifically recorded that she served Jesus means that the story ends with her submission to the Master (see Matthew 8:8–9).4
15 He touched her hand, and the fever left her, and she rose and began to serve him.