New Jersey did a State Census in between the Federal Census. In 1895, Ocean County, Dover Township there is a Margaret Caldwell, white female, age over 60. The only other person in her household is a James Caldwell, white male, age 20-60. That is the only information given in the 1895 State census, it does not have relationship or birth place.
John T Caldwell was born April 6, 1820 and died Oct 10, 1884. He is buried in the Whitesville Methodist Church cemetery in Jackson Township, Ocean County. According to his tomestone he served in the 4th Bat'ty, Art'y of NJ. I checked the New Jersey Courier newspaper published in Toms River. could not find an obituary.
John T Caldwell applied for a Civil War Pension, Feb 28, 1882. His widow, M. A. Caldwell applied for a widows pension Jan ?. 1885