Ecommerce website + 2 Mobile App maintenance

Yearly Maintenance Contract for my client:

Maintenance required for e-commerce website with 2 Mobile Apps (IOS / Android)

Regular site audits / clean junks
Fix bugs anytime
CMS security
Update CMS with plugins
Daily Scan
Patch update when needed
Mobile applications support
API update / Plugins update
New functionality development

Please quote your monthly charges + Details of how you perform the above tasks.