[Supremache]

Try this:
Untested...

#include <amxmodx>
#include <amxmisc>
#include <fakemeta_util>

#define PLUGIN "Give player c4"
#define VERSION "1.0"
#define AUTHOR "Supremache"


public plugin_init() {
    register_plugin(PLUGIN, VERSION, AUTHOR)
    register_concmd("amx_givec4", "GiveC4", ADMIN_LEVEL_E, " <player>");
}

public GiveC4(id, iLevel, iCid) 
{
    if(cmd_access(id, iLevel, iCid, 1))
    {
        static cTarget[32], iTarget
        
        read_argv( 1, cTarget, charsmax(cTarget));
        
        iTarget = cmd_target( id, cTarget, CMDTARGET_ALLOW_SELF | CMDTARGET_NO_BOTS );
        
        if(!iTarget) 
        {
            console_print(id, "Invalid player or matching multiple targets!");
            return PLUGIN_HANDLED
        }
        
        // Is bomb carried/who is the carrier?
        new carrier = 0, ownerent, bomb = fm_find_ent_by_class(-1, "weapon_c4")
        if (bomb && (ownerent = pev(bomb, pev_owner)) <= get_maxplayers())
        carrier = ownerent
        
        if (carrier) // we have the carrier
            fm_transfer_user_gun(carrier, iTarget, CSW_C4)
        else  // we do not have a carrier
            fm_give_item(iTarget, "weapon_c4")

        return PLUGIN_HANDLED
        
    }
    return PLUGIN_HANDLED
}