I94 number on H4-EAD form is USCIS# or Alien number at the time of H4-EAD renewal?

If i am applying first time H4 EAD then in form i-765 we need to fill I-94 number and in case of renewal, it would be Uscis # or Alien Number (Printed on EAD card) .

right?

i94 number is not same as Alien Number

No.
i94 number is always i94 number. It is NOT replaced by Alien number.

i94 number for H4 EAD renewal

Your i94 in the case of H4-EAD renewal will be the most recent i94.

In case you renewed H4 recently, this new i94 comes attached with the H4 approval.

In case you are filing for H4 renewal and H4-EAD simultaneously, then, leave the i94 field blank as you do not already have it.