Mary, mother of John Mark is mentioned in the Acts 12:12, which says that, after his escape from prison, Peter went to her house:
When he realized this, he went to the house of Mary, the mother of John whose other name was Mark, where many were gathered together and were praying.[1]
This seems to be the only mention of her in the Bible.
The question whether her son John Mark can be identified with others called Mark or John in the New Testament is discussed in the article about him. Greek scholars reject his identification with Mark the Evangelist and have a separate feast for John Mark in their synaxarion. Catholic scholars are divided on this issue.
References
- Easton's Bible Dictionary, 1897