Blood and hair follicles from 25 people put on the Moon; enough to regenerate a human population?
If we assume for a moment that the samples could be successfully cloned, 25 individuals is probably not enough to maintain a stable human population for more than a few hundred year without experiencing severe inbreeding depression and eventual extinction.  

In population biology, there's a general rule of 50/500 for minimum viable population sizes. Essentially, a minimum population of 50 is needed to prevent inbreeding depression, and 500 to stabilize genetic drift. Of course that's a generalization used in management situations, and lots of factors go into making a calculation like this with any amount of precision. 

One estimate gives a minimum viable human population (for generational space travel and permanent colonization) of ~40,000 humans in order to maintain genetic diversity. But that only applies to a population carefully screened and selected to maximize the effective population size. Another suggests 160 people could be enough for a stable population, as long as they return home to mix it up with the rest of humanity every 200 years or so.