Legally Blind, Widow. I am single. Do I also put head of household to get maximum standard deduction?

You cannot file Head of Household unless you have qualified dependent.  Do you have a qualified dependent?  If not, you file Single.

How long have you been widowed and do you have any dependents?

If you are single and you are legally blind, then your standard deduction is slightly higher than single. You can an additional $1,950 on top of the $14,600 for being legally blind.  

If you do not have dependents, you cannot claim head of household.