My grandmother remarried years ago, since that time both her and her husband passed away. Both had children from previous marriages. My grandmother had 5 living children at the time of death. Since that time 2 are deceased, one being my mother. Our family is seeking to obtain a clear deed on the property. In order to do so, does the property have to be signed over to one person in order to have a clear deed?

No, but it has to be conveyed from the last person of record to hold title to the property.

If, at the time of her death, someone petitioned the court to "probate" her estate, the executor should have executed a deed conveying title to one or more persons. Depending on what state or country she was residing in, and whether her husband was still alive at the time of her death, the property should have been conveyed to him &/or her children (from her previous marriage). If her since-deceased children received some portion of the property, their estates would also have to be probated.