It has been 17 years since my divorce which was within one year after giving birth to a son. Are there any methods for a lady to observe ceremonies such as mother-in-law’s sraddha, other tarppanam, etc.? Or are these not required? Have not received any alimony or wealth from my in-law’s place. Kindly advise.

Divorce is allowed only by law and not by scriptures. After marrying a male, a lady is his wife for life. This cannot be altered scripturally, even though divorce is allowed by law. Hence, the scriptures do not contain any regulations to follow for those who have divorced.
As per scriptures, a lady must perform the prescribed duties that are to be done along with her husband. This includes her duties for her in-laws that she must carry out. The moment a wife separates from her husband, she is unable to perform all the duties that need to be performed. It is wrong. Divorce itself is wrong. It should not have happened. There is no point in thinking or talking about other matters once this has taken place.