Question: Who owned the record company during which time Ritchie Valens sung the song most notably covered by Los Lobos?

Context paragraphs:
The Best of Ritchie Valens: The Best of Ritchie Valens is a greatest hits package by Ritchie Valens.

La Bamba (song): "La Bamba" has been covered by numerous artists, most notably by Los Lobos, whose version was the title track of the 1987 film "La Bamba" and reached No. 1 in the U.S. and UK singles charts in the same year.  The Los Lobos version remained No. 1 for three weeks in the summer of 1987.  The music video for Los Lobos' version, directed by Sherman Halsey, won the 1988 MTV Video Music Award for Best Video from a Film.

Ritchie Valens (album): Ritchie Valens is the first album by Ritchie Valens, posthumously released by Del-Fi Records in March 1959, one month after his death in a plane crash.  It is his only studio album entirely composed of master tracks recorded at Gold Star Studios.  The album peaked at #23 on the "Billboard" album chart.

Rock music in Mexico: Mexican rock music, often referred to in Mexico as rock nacional ("national rock"), originated in the 1950s.  Covers of standards by Chuck Berry, Elvis Presley and The Everly Brothers, by bands such as Los Rockets, Los Twisters, Los Teen Tops, , Los Locos del Ritmo, , Los Nómadas, and Javier Bátiz soon led to original compositions, often in English.  The group "Los Nómadas" was the first racially integrated band of the 1950s.  Their lead guitarist Bill Aken (Adopted son of Mexican movie actress Lupe Mayorga, said adoption making Aken the cousin to Ritchie Valens) wrote most of their original material, including the raucous "Donde-Donde", and co-wrote the material for their "Sounds Of The Barrio" album, which is still being sold.  Their 1954 recording of "She's My Babe" was the first top 40 'R & B' recording by a Latino band.  In the southwestern United States, Spanish guitar rhythms and Mexican musical influences may have inspired some of the music of American musicians Ritchie Valens, Danny Flores (of The Champs), Sam the Sham, Roy Orbison and later, Herb Alpert.  Initially, the public exhibited moderate interest in them, because of media attention paid to "La Ola Inglesa" (British Invasion).

History of Ritchie Valens: History of Ritchie Valens is a 3-record box set by Ritchie Valens, featuring his three original Del-Fi albums ("Ritchie Valens, Ritchie, & Ritchie Valens In Concert at Pacoima Jr.  High") plus a booklet with biography and photos (See each album title for contents).

Los Lobos: Los Lobos (] , Spanish for "the Wolves") is an American rock band from East Los Angeles, California, United States.  Their music is influenced by rock and roll, Tex-Mex, country, zydeco, folk, R&B, blues, brown-eyed soul, and traditional music such as cumbia, boleros and norteños.  It gained international stardom in 1987, when their cover version of Ritchie Valens' "La Bamba" topped the charts in the U.S., the UK and several other countries.  In 2015, it was nominated for induction into the Rock and Roll Hall of Fame.

Ritchie Valens Memorial Album: Ritchie Valens Memorial Album is the first greatest hits compilation by Ritchie Valens, featuring his first three charted hits plus tracks from the previous three albums.  The original album was issued with a black album cover and the same photo of Valens from his second album "Ritchie".  A few months later, the album was retitled "Ritchie Valens, His Greatest Hits" and repackaged with a white album cover and a photo of Ritchie taken from his Del-Fi EP "Ritchie Valens Sings" (DFEP-1111).  Both issues include the same back cover and album contents.

Ritchie Valens...His Greatest Hits Volume 2: Ritchie Valens...His Greatest Hits Volume 2 is the second greatest hits compilation by Ritchie Valens.  This follow-up to the "Ritchie Valens Memorial Album/His Greatest Hits" includes Valens' last two charted singles and ten tracks from the three original albums.  Three tracks were previously issued on the first greatest hits package: "Donna", "La Bamba" and "Cry, Cry, Cry"

Lasagna (song): "Lasagna" is a song by "Weird Al" Yankovic.  It is a parody of "La Bamba", a traditional song popularized by Ritchie Valens and Los Lobos.

Del-Fi Records: Del-Fi Records was an American record label based in Hollywood, California and owned by Bob Keane.  The label's first single released was "Caravan" by Henri Rose released in 1958; however, the label was most famous for signing Ritchie Valens.  Valens' first single for the label was "Come On Let's Go", which was a hit.  His next single, "Donna"/"La Bamba", was an even bigger big hit, and brought notability to the label.  Johnny Crawford, the co-star of the television series "The Rifleman", was the Del-Fi artist who recorded the most hit singles.  Del-Fi ceased operating in 1974.

Supporting paragraphs: Del-Fi Records La Bamba (song)
Answer: Bob Keane