The first priority for Marseille is to move up from fifth in the standings and put themselves into the champions league for next season and that is why they are desperate to sign the pair in the January transfer window.
Of the pair, Moreno is probably the easier target, he is out of favour at Anfield and his future with the Reds does look in doubt, he is just 26 years old and will not want to be spending his time on the bench, a move to Marseille would almost certainly guarantee him first team football on a more regular basis.
The situation with Monreal is not so clear-cut, he has been plagued with injury and it is uncertain how he fits in with Unai Emery plans at the Emirates, it is also not known if Emery would sanction a sale as Monreal provides significant experience at the back.
It should also be noted that the Gunners have lost Rob Holding for the season and the last thing that Emery would want to do his weaken his defence any further.
As things stand, it would be a likely yes with Moreno and a probable no with Monreal.