The incidents you refer to are found in Matthew 17:14-18, Mark 9:17-27, Luke 9:37-42.  It is edifying to read all three accounts and realize that while there are absolutely no errors or contradictions in the Bible, the three authors describe this incident in slightly different ways…showing their different perspectives on this event.  None of these descriptions are wrong, but the Lord used these men to describe this event from their own viewpoint. 

Matthew, Mark, and Luke all show that this incident with the young man occurred right after the Transfiguration of the Lord on a “high mountain.”  The name of the mountain is not mentioned in the New Testament, but most scholars believe it was Mount Tabor, a high mountain in Galilee.  From this, we can safely assume the occasion of this young man’s healing all refer to the same occurrence.

All three evangelists mention that it was this young boy’s father that brought him to the Lord. Luke 9:38 informs us that this was the man’s only child.  I want to pause right here and point out an important lesson for us who are parents.  May we all realize the importance of leading our children to the Lord.  By our words, our actions, and our example…we will influence our children to come to the Lord, or if our behavior and words are sinful, we will influence our children AWAY from the Lord.  What a wondrous and serious responsibility we have of bringing our children to the Lord and laying them at his feet.  We have such a nice example of Timothy being led to faith in the Lord Jesus in 2 Timothy 1:5 which says, “When I call to remembrance the unfeigned faith that is in thee, which dwelt first in thy grandmother Lois, and thy mother Eunice; and I am persuaded that in thee also.”  How nice of the Lord to show us that Timothy’s faith was influenced by the faithful witness of his mother and his grandmother.

• Matthew tells us that this child was a lunatic.  Several translations of the Bible (such as NKJV, RSV, WEB, and others) say he was epileptic.  Other translations of the Bible (such as ESV, NASB, NIV, and others) tell us that he suffered from seizures.
• Mark says of this young man that he had a “dumb spirit”, indicating he was possessed by a spirit that deprived him from speaking.
• Luke says that a spirit had taken him.  He is, of course, referring to an evil spirit. 

All three speak of the irrational behavior of this youth.  We read in Luke 9:39, “And, lo, a spirit taketh him, and he suddenly crieth out; and it teareth him that he foameth again, and bruising him hardly departeth from him.”  The Lord Jesus knew exactly what the problem was, and we read in all three accounts that the Lord healed this child from his helpless condition. “And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour.” (Matthew 17:18).  How great and discerning the power of the Lord that He knew exactly what the young boy needed, and He ministered relief and deliverance to him. 

I am so sorry to learn of the severe epilepsy that your young family member suffers from.  Does that mean she is demon possessed?  No, it doesn’t mean that at all.  Epilepsy is a diagnosable neurological disorder from which many suffer. From the Mayo Clinic’s website, we learn that “Treatment with medicines or sometimes surgery can control seizures for most people with epilepsy. Some people require lifelong treatment. For others, seizures go away. Some children with epilepsy may outgrow the condition with age.”  Perhaps your young family member will, indeed, outgrow this epilepsy.  Perhaps she will deal with it for the rest of her life.  May we all be acutely aware that our dear savior knows, understands, and cares about all our illnesses or infirmities.  We learn in Hebrews 4:15-16, “For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.”  Whatever the need is, may we all learn to “come boldly unto the throne of grace.”  Maybe the Lord will see fit to heal your family member.  Perhaps He will give her the strength to endure it.  Whatever He allows, we are assured that, “Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.” (James 1:17).  Whatever the Lord allows to happen is a good gift from Himself.  Trust Him as you continue praying for His perfect will!  (CC)  (662.2)