B2 to F1 to OPT - Stamping

[jaipalvyza]

Hello All my brother came to us on B2 on feb 2015 and applied COS to F1 on may 2015 and got approved on feb 2016 and continued college on dec 2016 college accreditation gone change to another university and completed graduation and applied for opt and opt start date on oct 1st 2018 and started payroll from oct 1st 2018. my father expired on jan 2019 came to india went for stamping his visa was rejected and gave 214b reason for 4 years completed 1 degree ? even attended stamping in Canada there also rejected gave 214(b) reason completed 1 degree in 4years and transferred college from after accreditation loss from that university.

Please suggest best way to get visa stamping and can he attend interview multiple times ?