I cannot find him in the West Virginia death records.

Her death certificate records Martha Jane Darlington, age 94, born 25 Feb 1862 in Beards Fork, W. Va., died 4 Jan 1957 in Deepwater, Fayette Co., West Virginia, usual residence Kincaid, W.Va., widowed, father Henry Taylor, mother’s maiden name Myriam Johnson, cause of death ventricular fibrillation due to myocardial infarction due to arteriosclerotic heart disease, informant Mrs. James Petry, burial in Johnson Branch Cemetery. (Mrs. James Petry is her daughter Della.)

Online West Virginia vital statistics28 contain a scanned marriage license and return for William Darlington, age 22, and Martha J. Taylor, age 23, on 10 Feb 1887 in Fayette Co., both bride and groom residents of and born in Fayette Co. (At the time they were born, West Virginia had not yet been formed.)

1900 census of Fayette Co., West Virginia, Kanawha district, enumerated 29 June, lists on p. 9B as family #163:
Darlington, William, 38, b. May 1862, farm laborer; Martha J., wife, 38, b. Feb 1863, married 13 years, mother of 4 children, 4 living; Della, dau, 11, b. July 1888; Mason, son, 10, b. Jan 1890; Gertrude, dau, 5, b. Sep 1894; Thomas A., son, 2, b. June 1897. John J., father 73, b. July 1826, widowed, b. WVa Tenn WVa. All except John born WVa WVa WVa.

1910 census of Fayette Co., West Virginia, Kanawha district, Kincaid precinct, enumerated 5 May, lists on p. 20A as family #391/408:
Darlington, William, 45, farmer; Martha, wife, 46, first marriage for both, married 22 years, mother of 5 children (#living too faint to see, possibly even blank); Mason, son, 19, motor man at coal mine; Thomas A., son, 12; Ida, dau, 6. All born WVa WVa WVa.

1920 census of Fayette Co., West Virginia, Kincaid precinct, enumerated 29 Jan, lists on p. 21B as family #59:
Darlington, Martha, 52, widowed; Thomas, son, 22, single, motorman at coal mine; Ida, dau, 16; Mary E., niece, 11/12. All born WVa U.S. U.S. (This census taker entered U.S. in nearly all of the parental birthplace fields.)