Your friend was within his rights to gift you his fish, and you were within your rights to accept them. However, without proof these fish were actually taken legally by another licensed angler, any wildlife officer to whom you showed your fish in the parking lot or along the way would determine you and your husband were in possession of an over limit.
To avoid a misunderstanding like this, the best way to have handled it would have been to ask the angler giving you his additional fish to write you a note clearly stating this. The note should contain the date, his name, address, telephone number and fishing license number so the note and your story could be verified, if necessary. Otherwise, you would likely be cited for being in possession of too many fish.
The only way to legally do what you are proposing is to make the entire dinner “a donation.” As long as everyone going through the meal line is not “required to pay,” there is no prohibition from calling it an abalone dinner.
While every angler must have a valid sport fishing license in possession while fishing in California, the law does allow a person diving from a boat to keep the license on the boat, and a person diving from shore may keep the license on shore within 500 yards.