Oh dear - the 1851 census entry (Ancestry) clearly says that Maria Aston (widow, aged 40) was born in "Hertfordshire, Sussex", and other entries show that the enumerator was writing the county name first. Worse still the family appears in the 1861 census - but only the children - Maria is not present.

As far as I can gather - looking at the most likely sources - there is nowhere in Hertfordshire which starts with "S" which could be confused with "Sussex".

So I took a different approach and did a blanket search on Ancestry for anyone who was recorded on any census between 1851 and 1901 born in "Hertfordshire, Sussex" - to see what went wrong in those cases. I found there were five independent cases, including Maria. I checked a couple to see what they might be and one was an indexing error for "Hertfield, Sussex" and none that I looked at were born in Hertfordshire in other census years. I then went to GenUKI to look at place names in Sussex - and I suspect your Maria was born in Hartfield, Sussex, or perhaps Henfield, Sussex.

As you seem uncertain about Maria's maiden name, and as the census shows she had children born after 1837, you should be able to get her name from one of the younger children's birth certificates.

If you can add to the information given above tell me.