As far as I know, Tottenham is also interested in Mbeumo, but it seems they are not making a higher offer than Man United, so in this case, Man United has a better chance to sign Bryan Mbeumo. Brentford have set their price, and Man United look set to meet it, so if Brentford are willing to ask for a higher price again and again, then it is likely that Man United will step down.
If Bryan Mbeumo does join Man United, then he will soon meet up with his compatriot (Andre Onana), and I think Andre Onana may have played a part in Mbeumo joining Man United.
Tottenham won't be making a high bid like Manchester United so I'm sure they won't be in the running. Manchester United are more realistic now because they don't rush to sign players at the prices their parent clubs are asking and now Manchester United are much more careful in considering the signings they need. It was different before because they were so quick to act even though the asking price was quite high and now the difference looks much better.
Bryan Mbeumo is really needed because he is a hard working player and last season he made a real contribution for Brentford. Onana could be the entry point because they are both from the same country and it would be much better if Bryan Mbeumo joined Manchester United.