According to Buddhism what is Arahants and Lohans?

Are all Monks can become arrant after they die

Essentially, an Arahant is someone who achieves enlightenment and becomes a Buddha. This does not happen AFTER death but before so that the cycle of Samara ceases. Not all Monks can achieve Arahant. A Lohan is just the Theravada translation of Arahant in Chinese.

Hi Datuk ...
Wanted to refer you on to these two sites:

This one will help you find drama centers for listings around the world:
http://www.dharmanet.org/listings/

These sites are Buddhist forums, specifically for those interested in Buddhism. As with all forum sites, people will be newcomers, some will be more knowledgeable. But, in general, you will find a more people knowledgeable about Buddhism on these sites than on Y/A:
http://newbuddhist.com/forum/index.php
http://www.buddhismwithoutboundaries.com/

I have comments to make from time to time, but I do not consider myself worthy of being a teacher.

Well, I have told you before what is Arahat in one of your previous questions:
http://nz.answers.yahoo.com/question/index;_ylt=AtTDlbggrdL7YrgkY9xK4X3JZwx.;_ylv=3?qid =20101025064723AA9Bztz

Lohan is the Chinese translation of Arahat, meaning they both are the same.

A monk may become an Arahat before or after they die, depending on the chains they have broken. If they haven't reach Arahat state enlightenment in their present life, they may reach it in their next life(s).