Is PG Diploma in MBA from IIMA-Meerut, valid?

Prior to taking admission in IIMA - Meerut, you should have examined the validity of the course in terms of its UGC recognition apart from the course approval from AICTE.
There could be confusion in the selection of right courses since the aspirants might be misled with the IIM tag but all the courses with such a tag might not be valid both from UGC angle and from AICTE approval.
Hence producing this certificate before the employer will not produce any beneficial effects.

The institute did not have valid registration from UGC or any other authority for providing any such course to the aspiring students. Many students were in fact misled by the institute's advertisements about it. As per the information available, it seems that the institute also did not claim for having any such approval and in due course of time it was closed to provide any such ambiguous course. Many students have mentioned about this institute that their degree/diploma acquired was not considered valid and it was a loss of time and money for them. I do not think that you can do anything about the matter now. There were many such institutes in our country which offered ambiguous courses to the students and when a large number of complaints were made they disappeared from the scene or were closed by the authorities. I think students have to be very careful about these aspects before joining a course in any institute.

The Institute is not having any UGC recognition and the institute never mentioned its recognition only. There are many such institutes offering PG diplomas and diploma courses. If we study our basic degrees like BA or BSc or BCom or BE or BTech etc from such organisations, those are not considered for giving you a job. That is what your friend told you also.
But additional qualifications like these diplomas and PG diplomas can be obtained by them. If the recruiters say that you have to have a diploma or PG diploma from a recognised institute, the certificate obtained from you is not valid. The government organisations will not consider it, But if you are applying for private jobs you can mention this qualification in your CV and they may take this also as an additional qualification. Whether they consider it or not you can mention the same as an additional qualification.
But please remember that one should check the status of the institute we are joining for a course and once we are satisfied only we should join. Otherwise, after completing the course you can't do anything.