what evidence does a 60 year old LPR mom need to provide for after filing for her 18 year old son, or is a dna required in this type of case

Usually, a birth certificate establishing the mother-child relationship is sufficient for immigration purposes. However, if there is no birth certificate or there are other reasons to question the validity of the document, additional evidence may be requested such as baptismal or other religious records, early school records, other government records, affidavits, etc. where secondary evidence is not sufficient, DNA testing may be required. You can read more about family immigration at http://myattorneyusa.com/family-immigration.