I have sc caste certificate of up but since 20 years we are living in mumbai and have domicil ccertificate is im eligible for state quota
Caste certificate and domicile certificate are 2 different things. If you have a domicile of Mumbai yes you can apply and show your caste category as well.
Yes you are eligible for state quota (through Mumbai domicile)
Hope this helps.
All the best.