The Ask toolbar may have been installed along with another toolbar or program. It also might change your home page in Firefox. Do either of these recent discussions help?

Can not remove "Ask Toolbar" from FF in windows 7 | Firefox Support Forum | Firefox Help

ask browser keeps coming back how do I permanently remove it | Firefox Support Forum | Firefox Help

If there is a problem with the about:home Home page then try to reset the search engine used on the about:home page.

Reset the browser.startup.homepage_override.mstone pref via the right-click context menu to the default on the about:config page and close and restart Firefox to restore the about:home page to its default.

• Open the about:config page via the location bar
• Type in the Filter bar: mstone
• Right-click the browser.startup.homepage_override.mstone line and select: Reset
• Close and restart Firefox

If that didn't help then delete the delete the chromeappsstore.sqlite file in the Firefox Profile Folder and repeat the above.