I couldn't find any mention of Tottenham also being interested in Mbeumo, I see that only Manchester United are negotiating for him and it looks like they will come to an agreement for €70 million. Manchester United have already paid €73 million for Cunha, they want to strengthen their attack. But what about the defense, they need a stronger goalkeeper and a couple of reliable defenders wouldn't hurt either.
Whether they show Interest or not Mbeumo has already made it clear to Brentford that his dream destination is Manchester United and I believe that's where he'll end up going to, Manchester United made an improved offer that's fair enough but Brentford are too greedy they want a fee close or slightly to what Manchchester United paid for Cunha. As for a goal keeper they'll only sign one if they can secure a deal for Onana or Bayindir to leave and names like Marco Carnesecchi of Atlanta, Martinez of Aston Villa and Diogo Costa of Porto fc have been picked as a potential replacement for Onana, the only defence position i feel Manchester might look into is the right wing back.