A few other people help the Żabińskis along the way. Most of their allies are the usual suspects. For example, you would expect old ladies to be kind and grandmotherly and help out those in need. Mrs. Cederska and Mrs. Stokowska are Antonina's kindly landladies the first time she flees the villa, and true to form, these surrogate grandmas totally feed Antonina and her son and play games with them. Later, when they flee again, assisted by the Fox Man, they are fed by Mrs. Kokot, a nice schoolteacher.
One of their allies is unexpected: a German. Dr. Müller is a fellow member of the International Association of Zoo Directors. He helps Jan when Jan finds himself in a bind: "The best plan, he suggested, was to arrest Jan and drive to Warsaw with him as a prisoner; and despite their past cordiality, Jan worried if Müller could be trusted" (6.17).
Yeah, that's pretty scary. Luckily for Jan, Müller could be trusted, showing us that for some people (i.e., not Lutz Heck) the brotherhood of zookeepers, and the brotherhood of basic human decency, can be stronger than political affiliations.