Slight bleeding post menopause is ok it is because of hormonal imbalance where in body is still getting adjusted to the new phase of life. This may happen for few months then gradually it will stop. Usually if u go to allopathic practioner they start off with hormonal therapy. You can also give ayurvedic medicine or treatment for it which she will need to take for few months.
Next Steps
u can wait and watch for 2-3 more cycles if no other fresh complaints give body time to adjust but if it becomes trouble some she can start with treatment.