Is it safe to take metronidazole with milk?

Yes. There is no known contraindication to taking Metronidazole with milk; however, you avoid taking any alcoholic beverages with metronidazole.
Yes. Metronidazole and milk don’t interact, so you’ll be in good shape if you want to drink milk while taking metronidazole. The only dietary consideration to keep in mind is that one must avoid alcohol while taking the drug and for about four days afterward (this may or may not be relevant to you).