You may try this..
If you apply distinct on a datetime part it will return all the rows. So its better to convert/cast into a date.
declare @LoginTable table (LOGINTIME DATETIME,UserId int,CompanyName varchar(100),EmailId varchar(50),
RegistrationNumber varchar(50),Name Varchar(50))
INSERT INTO @LoginTable VALUES('2017-03-29 17:00:48.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-29 17:29:02.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-30 10:22:46.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-30 11:16:23.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-30 11:25:26.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-30 11:30:16.000',1,'M/s. Fauna International','faunainternationalhr@gmail.com','TN2/ME/033/04','Tamilnadu')
INSERT INTO @LoginTable VALUES('2017-03-30 14:32:13.000', 1206,'afzal kader and company','afzalkader@libertyfoods.ina',NULL,'Andhra Pradesh')
INSERT INTO @LoginTable VALUES('2017-03-30 14:40:31.000', 771 ,'Kalyan Aqua & Marine Exports India P Ltd',' kalyanaquafarms@gmail.com','AP1/MT/143/12','Andhra Pradesh')
INSERT INTO @LoginTable VALUES('2017-03-30 14:53:16.000', 771 ,'Kalyan Aqua & Marine Exports India P Ltd ','kalyanaquafarms@gmail.com',' AP1/MT/143/12','Andhra Pradesh')
INSERT INTO @LoginTable VALUES('2017-03-30 14:56:49.000', 543 ,'Kader Exports Pvt. Ltd.','afzalkader@libertyfoods.in','MA1/MT/009/05','Maharashtra')
SELECT DISTINCT CAST(LOGINTIME AS DATE) AS distLoginDate,ER.UserId,ER.CompanyName,ER.EmailId,ER.RegistrationNumber,ER.Name
FROM @LoginTable ER
WHERE ER.LOGINTIME BETWEEN '2017-01-01' AND '2017-12-31'
GROUP BY LOGINTIME, ER.UserId,ER.CompanyName,ER.EmailId,ER.RegistrationNumber,ER.Name