Dehydrated disc, bulge at c5-c6 will fasting in the month of ramadan make the dehydration worse? can i hydrate the disc?

No and No: "Dehydration" of the disc material refers more to changes in the collagen content of the disc. Fasting will not aggravate this type of "dehydration" of the disc. There is nothing that you can use to "rehydrate" the disc either. A "Bulging" disc is a VERY COMMON finding on MRI: it does not correlate very well with the presence/absence of symptoms; "bulging" by itself does not result in problems.