Lies or truth


HELP... my step son is 5 and has slipt time between us (me stepmum and his dad) and his mum. Today he was playing with his toy tiger and hit him on the head several times. I said dont hit him thats not nice, he said it is okay mummys friend hits me on the head and mummy lets her. After talking to him for abit he said it was a lie.. this isnt the 1st time he has said this but it is always about a differnt doing the hitting but then ends up saying it was a lie.. is he lieing for attention or is he trying to tell me but then backs out because he is scared. please help? Any advise would be amazing..