Mark's answer is correct, but in my opinion is not clear enough. Let's make it a bit simpler:
Is it possible that the geomagnetic field reversal led to the extinction of Dinosaurs?
NO, DEFINITELY NOT
The cause for the K-Pg extinction event (in which many living species, including dinosaurs, died) is well known: volcanic eruptions (the Deccan Traps) and an impact (Chicxulub). It's still debated which one contributed more to the event, or whether one is the result of the other, but that's not the point. It's not related to magnetism.
In fact, all big five extinction events in Earth's history are well linked to increased volcanic activity (including the Siberian Traps at the time of the largest extinction, the P-T extinction event aka the "great dying").
On the other hand, magnetic reversals happen all the time. Yet, there are no extinctions related to them. Your question also lists several incorrect assumptions:
continuous meteor bombardment
Incorrect: Geomagnetic reversals have no effect on whether we are bombarded by meteors or not.
raised volcanic and tectonic activities
Incorrect: Geomagnetic reversals are not linked to raised volcanic or tectonic activity.
Between Matuyama Epoch of 243 million ya to 68 million years ago to Brunhes-Matuyama current epoch
These are recent magnetic epochs from the Pleistocene, only a few million years ago. Thus unrelated to the K-Pg extinction event (or any event for that matter).