Attitude toward our son

So last week my father in law passed away, it has been rough few days but my husband has been better than I thought. Our son is 2 and at the moment he isnt being the easiest (terrible twos have hit).

We share a home with my Mother who has told me today that she has heard my husband tell our son he hates him, told him to piss off and for example today... i was cooking and our son was with me. It became too much so sent him in the living room with his nan and my husband (his dad by the way) and he was upset so i sais go to daddy. He walked up to my mum crying because he done that he said oh piss off then...

O dont know how to broach the subject. I know he wouldnt hurt our son, he doates over him but our son does get babied by me and my mum so he likes that.

Help