Taxpayers do not claim their spouse as a dependent. They are listed as sharing the return.
It could be possible for your mother to file a separate return (only claiming herself) if your father is your dependent (if you supply more that half your father's support).
According to the IRS:
Some people cannot be claimed as your dependent. Generally, you may not claim a married person as a dependent if they file a joint return with their spouse.
IRS LINK
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