Your pup will have a certain amount of antibodies from the mother. Your pup also was around the mother in the later weeks when she would have gone out (for walks etc.) so she would have been exposed to some diseases, if the people had more dogs than the mother then all those dogs would have been coming and going as normal.
Best to use common sense, your garden should be OK (within reason - don't put her outside for an hour!). It is just best not to take the pup to the local park where tons of dogs go! (and don't let her sniff to much or lick where other dogs have been). Also leptro is spread by rats urine so don't let her drink out of any puddles of rainwater in the garden. Also make sure the hunt dogs are not around when you have her out (don't want them to mistake her for prey!).
Basically, just use common sense. Of course you will bring stuff into the house on your shoes etc. but your pup should have enough natural defences to combat this, especially if she is happy and healthy.
It is important to socialise her, I would rather take the very slim chance of infection than have a nervous, unsocialised dog that was scared of everything! If she is small enough for you to carry around I would also get her out and about that way.