A lamp inscribed on a tombstone symbolizes immortality of the spirit and resurrection. It may also symbolize wisdom, faithfulness, and holiness.
A lamp creates light and its purpose is to bring light to darkness. A lamp and light are mentioned a number of times in the Bible and here are just a few:
For you are my lamp, O Lord, and my God lightens my darkness. (2 Samuel 22:29)
Your word is a lamp to my feet and a light to my path. (Psalm 119:105)
For the commandment is a lamp and the teaching is light…(Proverbs 6:23)
The spirit of man is the lamp of the Lord, searching all his innermost parts. (Proverbs 20:27)
For it is you who light my lamp; The Lord my God lightens my darkness. (Psalm 18:28)
In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven. (Matthew 5:16)