Neighbor table of End device

According to my experiences, I can get LQI of child node and neighbor node using ZDP_MgmtLqiReq. What do you mean you didn't get right value?

nwkAddr is zero for two entries ie, coordinator address. Even if the parent router is connected to another router,the second router address is missing

Can you show me how you use API ZDP_MgmtLqiReq?

index=0;
dev_addr.addrMode = (afAddrMode_t)Addr16Bit;
dev_addr.addr.shortAddr = NLME_GetCoordShortAddr();
result = (uint8)ZDP_MgmtLqiReq(&dev_addr,index,0); // called from GenericApp.c of End device

Response message is parsed as follows
case Mgmt_Lqi_rsp:
ZDO_MgmtLqiRsp_t *pLqi;
pLqi = ZDO_ParseMgmtLqiRsp(inMsg);
if (pLqi)
{
lqi_ret.status = pLqi->status;
lqi_ret.neighborLqiEntries = pLqi->neighborLqiEntries;
lqi_ret.startIndex = pLqi->startIndex;
lqi_ret.neighborLqiCount = pLqi->neighborLqiCount;
for(int nItem = 0; nItem < lqi_ret.neighborLqiEntries && nItem < MAX_LQI_ITEMS; nItem++)
osal_memcpy( &lqi_item[nItem], &pLqi->list[nItem], sizeof(neighborLqiItem_t) );
}

NLME_GetCoordShortAddr means to get short address of current device's parent node. Do you intend to do so?

Yes, also the number of neighbor table entries is 2, even if more than 2 routers are there

The neighbor table is manipulated by Z-Stack. You might have more than 2 routers are there but Z-Stack might only use 2.

But in my End device application, I need parent router address as well as two near by routers with LQI values. Is this possible ?

It's no problem to get LQI of parent node but it is also no guarantee to have LQI of two neighboring routers.