The original song is from Shiraz where the accent has a tendency to turn final "â" sounds into "o" (oy, yârom, bio, etc.). Neither artist is from Shiraz though, so they miss some of them! The standard pronunciation is "yâram" anyway. Note that the word should be written as "یارم" even if you want to convey the Shirazi accent, since the final vowel would be the short "o" and not the long "u".

Yaram is correct for you. But yarom is not correct, It's because of the dialect in south of Iran. In some southern citis this dialect is used.

"Yarm" is the correct Pronunciation. But when we are singing we extend the tone and in persian or Arabic is more extended as well you hear Yaram or Yaaromm but only the first pronounce is correct to یارم. The Persian word has also passed into Turkish : yaRm is said to mean «agat» at Kazan (RADLov, III, 247), but it is quite certain that Osm. yäsäm or yäsäp means «jade ». look here: http://dsr.nii.ac.jp/toyobunko/III-2-F-c-104/V-1/page/0440.html.en

Yes the song says "yarom". But as others said "yaram" is a standard accent in Farsi. But "yarom" and many words like this are used in some local accent. By the way I've heard this song originality comes from Tajikistan. Good luck.